Architect delays renovation and forgets agreements. What to do?

That's right! He gets good money for his performance!

That sounds really good, I’m keeping my fingers crossed for you that something starts moving now!

and yesterday late in the evening sent a schedule. It looks just as I imagined (a Gantt chart with all upcoming steps).

The forms of visualization are different, and not every client is grateful for this form. In my opinion, a form compatible with laypersons would be a text format with one sheet per week, divided into 1. a list of the projects to be carried out as planned; 2. explained deviations from the plan; and 3. measures to restore plan congruence (with a success report). So, for example, trade H will be there and is supposed to take four days; trade I has to postpone its arrival; trade J cannot yet carry out its planned work because of this, but will already come to chisel away what trade G built too wide. The plan for the next week can be executed as intended. Trade I will come three weeks later. Trade J will return for its planned work in four weeks because it follows trade I but has no time in three weeks. Reading this from a bar matrix requires practice, which one cannot assume in a layperson client – which the single-family house client usually is :)

Status update: we have received a schedule. Although it still needs to be corrected and supplemented in one or two places, it at least represents a starting point. At the moment, there are problems with the screed layer, hopefully this won't throw everything into disarray again.

However, our architect will definitely never become an organizational talent; he has just finished planning how we will proceed regarding our extension and the partition wall to the neighboring terraces. I might create a separate thread about this, as both I and the neighbors think the solution found is stupid.

Das aus einer Balkenmatrix herauszulesen, braucht Übung, die man beim Laienbauherren - was der Einfamilienhaus-Bauherr ja meistens ist - nicht voraussetzen kann

That is certainly a matter of practice. I know it like this and also find it very clear that you set up dependencies with a WBS (Work Breakdown Structure) and then break down the whole thing temporally with the help of a Gantt chart. All the more frustrating was that in our case we had to chase such a thing for months.

Nice to see progress. You seem to be gaining some ground.

Interim status: we have received a schedule. Although it still needs to be corrected and supplemented in one or two places, it at least represents a starting point. At the moment, there is a problem with the screed layer, hopefully that won't throw everything into chaos again.

I already said that what distinguishes the plan from a report is that the plan is active. A plan that only works under the unlikely condition of zero deviation or does not provide effective corrective measures for deviations is worthless. That is neither a plan nor a report, but a wish protocol.