The farm has roof damage

Dear experts and renovation professionals,
my husband and I have come across a small farm with a main house from around 1800 that we have fallen head over heels in love with. The previous owner has done a lot of the work himself over the past 5 years, and the energy certificate and heating system are new. The bathrooms are new and high-quality, and the electrical wiring has been renewed in the bathrooms as well as in the new kitchen. The small farm should cost around 80,000 euros and we were already about to seal the deal until someone advised us against it. Reason: The ceilings upstairs are extremely low-hung! We thought (we are both not experts) this was normal for an old farmhouse and could be changed. However, all the clad wall beams upstairs are not straight; they sag slightly downward and 3 of the 4 room ceilings bulge downward. Only one single beam is exposed. On this one, there is a slight worm infestation visible. The current owner says the beam was inspected and treated before he moved in and that everything is okay.
We then went up to the unfinished attic with our "expert," who said that is the problem because the ceiling can no longer bear the weight of the old clay insulation, and to change this, everything would have to be removed and newly insulated and the ceilings lifted at the same time.
His opinion: All the clad beams are defective, otherwise they would not sag slightly, and if we are unlucky, they could be eaten through by worm infestation.
In the attic, all visible roof beams as well as floor beams were free of holes and also not affected by mold or moisture.
What do you think?
Big risk or normal renovation factor in an old house? With what sums should we reckon in the very worst case if the beams really have to be exposed and replaced (we would like to at least tackle the removal of the ceilings and the old clay layer ourselves)?

Problem 2
What is probably much worse: The house is connected with an attached barn and a small stable by a large roof. It is practically a slightly U-shaped structure. The previous owner says that although the concrete tiles are not visually appealing anymore, they are still watertight. Our helper said the roof must be completely redone because the tiles are already disintegrating. The owner's idea was to tear down the barn and stable to ground floor height and build a flat or slightly sloped roof there to save costs. He said one could reuse the still completely intact roof parts (beams).
Our helper himself comes from the drywall sector and threw out wild numbers that scared us. We know that a new roof covering over this area will cost a lot of money; the question is whether it makes sense, financially and looking to the future, to reroof or actually tear it down.
What do you think?
What costs should we expect there?
I know this is hardly or not at all estimable without viewing and this is about a second opinion and a rough estimate of the scale we are dealing with here. Should we actually decide on this little farm dream?
Is there a cost-effective option? =( Only roof the house with tiles and cover barn and stable with bitumen corrugated sheets? Does that make sense?

We are grateful for every friendly tip and advice/experience!
Steffi and Patrick#

General information about the farm (main house around 1800)
House: 130 sqm
Barn: Garage/heating room downstairs, only hayloft upstairs (not to be converted)
Stable: 3 horse boxes (not to be converted)
Energy certificate: Green 113 kW
Windows: New
Heating: New (wood gasifier)
Bathrooms: 2 bathrooms renovated this year, high-quality - electrical systems new
Kitchen: Renovated, electrical system new
Wastewater: Septic tank/connections for possible connection to city network already prepared
Courtyard/land: Well maintained
Terrace: Renovated
Other electrical work: Needs to be done
Purchase price: 80,000

Objectively seen and without love and without knowing the thing, you pay 80 for the land, it's definitely 1000 sqm of land if not more. 15-20 demolition. 100 new build 250. Adds up to 350 for a nice house with a large plot. Just think about it like that. Karsten

But we don't want to tear anything down and rebuild; we want to preserve the farm and live in it o.O!!! It is extremely rural, but that's exactly how we want it! And the plot is a total of 1000 sqm.

Nevertheless, economically speaking, the price is okay at 80. Take another 120 or 150 in hand, then the roof and ceiling are new.

What kind of "expert" or helper is this? Are these knowledgeable people?

Otherwise, here is my tip: invest in a "real" expert who also understands the numbers and does not say: if you are unlucky, it is worm infestation, but who definitely determines whether worm infestation is present. He should calculate for you what belongs in the purchase price at the top and how many years you can be happy with renovation.

That is the dad, he works in construction, specifically interior finishing. And the current owner has already done quite a bit with his dad (also in the construction industry). We will probably also do the building surveyor thing just to be on the safe side. We really thought maybe someone has bought and renovated a similar farm themselves and perhaps has some experience and tips for us.

Thank you ypg =))