The vapor barrier has a brownish position, insulation is wet

What I would still be interested in at this point. Although there is the rule of thumb that mold should not be expected below 70% relative humidity, can this also be applied to the insulation layer? The rule of thumb apparently primarily applies to the classic case, exterior wall, cold, mold. But if there is a leak in the insulation layer, more precisely in the vapor barrier/brake, is mold to be expected in the layer even at, for example, 50% relative humidity (at normal room temperature), or can one actually assume that no mold will develop because too little water is transmitted? How does a climate membrane that works in both directions operate? Does the relative humidity control the direction?

In the best case, yes, through expansion and thus enlargement of tiny holes nanometer-sized or even smaller. But I believe that apart from the manufacturer, no one and only a few could confirm whether and how all that is supposed to work. I also believe that the values could vary greatly depending on the region and environment.

Thank you very much for your effort. I have also contacted the manufacturer again regarding this and will keep you updated.

Here is the feedback from the manufacturer:

"Room air humidity around 70% can be considered safe from damage. At this moisture level, the mentioned hazards are only to be expected after a prolonged exposure period.
Depending on the duration and level of moisture load, the risk of hazards increases. Mineral materials are classified as more favorable regarding mold growth than organic materials.
Therefore, moisture of freshly installed wet building materials such as concrete, masonry, plaster, and screed should generally be quickly removed from the building or extracted from the building materials.
DIN 4108-7:2011-01 (Thermal insulation and energy saving in buildings - Part 7: Airtightness of buildings - Requirements, planning and execution recommendations, and examples) notes under 5 'Planning and execution' the following statement:

"... Building materials must not be unnecessarily exposed to excessive humidity during the construction phase. Therefore, sufficient dehumidification (e.g., ventilation) must be ensured."
Ideally, "dry living" of the building is not required, and interior finishing can be carried out directly, promptly, and without a ventilation gap to the exterior components.

Below are exemplary possibilities for practical implementation on site, as well as tips and notes. These must be adapted if necessary according to the specific conditions of the object and follow the sequence of construction measures.

The 60/2 and 70/1.5 Rule (Building Physics)
To protect constructions even at temporarily increased relative humidity (rel. RH), a vapor retarder should

[*]at 60% average rel. RH (e.g., new buildings or temporarily kitchens, bathrooms) achieve a diffusion resistance (sd-value) of at least 2 m
[*]at 70% average rel. RH (e.g., construction phase, see above) achieve an sd-value of at least 1.5 m. (see also)

pro clima vapor retarders such as INTELLO, INTELLO PLUS meet these requirements.

Planning Phase - Trade Sequence - Construction Process

[*]Building envelope closed, no insulation and no airtight layer, with: unplastered masonry, roof sealed, uninsulated
Initially, wet materials are installed (e.g., plaster, screed). After 2 - 3 weeks drying phase: installation of insulation and vapor retarder, step by step. Here, a mold risk arises for organic surfaces and an increase of the initial moisture in sorptive building materials.
[*]Building envelope closed, insulation installed and airtight layer closed, unplastered masonry, roof sealed and insulated
Wet materials are installed (e.g., plaster, screed). After max. 2 weeks rest phase, active dehumidification of the building.

Active Dehumidification

[*]Ventilation
Means a permanent, continuous day and night ventilation. A airflow must be generated across the entire building. Ventilating via, e.g., tilt windows or shock ventilation does not achieve sufficient moisture removal.
Supplementary heating supports the drying process during ventilation. Heating causes the moisture to be more strongly released from the wet building materials and then removed from the building by ventilation. Heating without continuous ventilation is therefore to be avoided.
Disadvantages of ventilation method: a) at too low outdoor temperatures, there is a risk that fresh plasters or wet screeds may be damaged and/or b) dry too quickly, as outdoor air, especially on cold days, is very dry.
[*]Technical Drying
Construction dryers take over the active dehumidification of the building. Generally, 1 - 2 construction dryers of average capacity in the attic of a residential building are sufficient to maintain an average, max. 70% rel. RH. The number of dryers depends decisively on the existing moisture, building volume, and drying capacity of the devices.

Measurement and Documentation of Air Humidity is Recommended
The entrapment of construction moisture in dry building materials or components (e.g., insulated rafter cavities) can lead to later mold growth.

Material Drying Times - Choice of Building Materials
Too rapid drying of wet building materials can lead to cracking or deformation. The specifications for required "curing times" or rest periods vary significantly and must be clarified with the respective manufacturer. The following are market-standard reference values: Cement screed: ~7 days, Calcium sulfate screed: ~2 days, Fast screed: ~1 day
During the "curing time," exceeding the average rel. RH of 70% is unavoidable. Active dehumidification of the building should begin no later than after 14 days.

Using fast-drying screeds is an effective method to minimize construction moisture and thereby reduce hazard potentials.

Dry and absorptive building materials, such as gypsum fiber/gypsum plasterboard, can buffer moisture peaks. The building materials used for buffering must be suitable for this purpose.

Planning adapted to the construction situation and coordination with the plasterer, as well as the coordination of work, is recommended. The construction management plays a key role here."

That has nothing to do with the humidity in the insulation. The relative humidity is already strongly increasing across the cross-section outward when it is warm inside and cold outside. It is important that the dew point is not undershot and that the upper covering is relatively diffusion-open. The latter is obviously not the case with you.

Yes, it doesn’t have much to do with my request, but even after my repeated specific inquiries, the manufacturer refers to the information mentioned. I suspect they don’t want to put themselves on thin ice and make a definite statement... unfortunately.

Exactly, the OSB certainly acts more as a brake or even a barrier for me, as we laid the panels with tongue and groove almost perfectly and screwed them every 8 cm. That’s exactly why I came up with the idea to deliberately drill holes or mill slots to allow some "breathing." (If you consider through which small pores of the membrane the moisture must have come in, almost 4-6 holes of 10 mm diameter on a 2.50x1.25 panel should be enough)

I suspect it will be a mix of everything, after the screed is in, the heating program is running, and the rough moisture is gone. Open the barrier, check the moisture, replace insulation in places for safety, and let the construction dryer work as soon as possible. Once the moisture levels below are correct and the wet construction sections are completed, the membrane should work properly.