Construction obligation in the purchase contract

I have a question about the draft purchase agreement for my plot of land. Under the "special agreements," the following passage is stated:

"Paragraph 13
The buyer commits to building a ready-to-move-in house on the plot by December 31, 2022. If the buyer does not construct the house within the agreed period, ... or the municipality ... has the right to purchase the plot at the buyer's expense.
The real estate transfer tax triggered by this legal transaction for ... or the municipality ... must be reimbursed immediately by the buyer. The buyer undertakes, in the event of a possible re-transfer, to transfer the plot free of encumbrances to ... or the municipality .... In this case, the buyer will receive the paid purchase price without interest compensation from ... or the municipality ... immediately after the registration in the land register. Any costs arising from the re-transfer must be borne by the buyer. Claims of the seller against the buyer, insofar as they arise from the contract in this case, can be offset.
To secure the conditional claim of ... or the municipality ... for transfer according to §13 para. 1 of this contract, the buyer already grants and applies for the entry of a conditional priority notice to secure the claim for conveyance in favor of ... or the municipality ... in the land register.
This right is subject to the priority for mortgage rights to be entered for financing purposes of the planned building project up to the amount of .......... € <- Note: free text field up to 20% interest p.a. from the day the mortgage is registered and 10% for one-time ancillary services. Compliance with the intended purpose does not have to be proven to the land registry office but upon request to ...
It is granted and applied for that the priority reservation is entered in the land register with the transfer priority notice.
... or the municipality ... undertakes to request the deletion of the re-transfer priority notice upon the buyer’s request once the building obligation is fulfilled. The buyer bears the costs of the deletion.
With the corresponding declaration and application, ... or the municipality is authorized to also act as the current notary when submitting the application. The buyer hereby waives unilateral application."

The goal is, of course, to acquire the house in order to build a residential house on the plot for my own use.

As far as I understand the passage, one cannot be forced to move in even after completion of the new building, right? Because it was stated somewhat differently in the exposé.

However, I am indeed wondering what concrete consequences it would have if, unexpectedly and unforeseeable at this time, I were to find myself in a situation that would prevent me from starting construction.

If the plot costs 100,000 €, I would have to pay the real estate transfer tax twice, once at purchase and once at the re-transfer to the municipality. That would mean costs of 2 x 5,000 € = 10,000 €.

The reimbursement price would be the 100,000 € without interest, correct? So I would have a loss of 10,000 €, assuming no further claims to offset, for example because I would not return the plot free of encumbrances. Or are there any other costs to be expected?

Furthermore, by signing, I would agree that it is noted in the land register that the municipality has a "repurchase right" if I have not built on the plot by December 31, 2022, right?

The paragraph regarding financing purposes is not clear to me. What is meant by this and what amount is appropriate for the free text field?

Also, the penultimate paragraph states that the buyer must bear the costs for the deletion of the re-transfer priority notice in the land register. How high are these costs?

What do you think generally about this paragraph? Is this usual or is there anything in it that one should preferably not sign?

Thank you very much in advance for your answers.

Yes, the clause regarding the building obligation is common. Not every municipality does it, but quite a few do. The aim is to avoid years of vacant building plots in new development areas.

However, you also get a plot of land at a price that you certainly wouldn't get "from private sellers."

You won't be able to circumvent this clause. If you can't or don't want to build on the plot, someone else will be happy. I understand that this clause unsettles you because you might not have expected it. What I don't understand is why you're worrying about some details now when you want to build anyway. Or what do you think could happen within 4 years that would prevent you from putting up a house?

By the way, there are online calculators on the internet for land register entries, deletions, notes of conveyance, etc., which are accurate to within one hundred euros.

The clause is usual and also fairly worded. In short: Building commitment is on the land, within 3 years the house has to be there, which can also be a rental house if applicable. I don't know the development plan. The financing clause ensures that the municipality does not put obstacles in your way during financing, since the bank with amount x, which depends on the loan, is given priority. - You should only buy this property if you want to build on it quickly, putting it aside and just waiting is not an option. Karsten

yes, common and sensible so that no [Grdunstückspekulanten] cause trouble

The clause is common and also quite fairly formulated. In short: There is a building commitment on the land, the house must be built within 3 years, which can also possibly be a rental house. I don’t know the development plan. The financing clause ensures that the municipality does not put any obstacles in your way for financing, as the bank is given priority with sum x, which depends on the loan. - You should only buy this plot if you want to build quickly; buying and just waiting to see is not an option. Karsten

It is actually almost 4 years, which is really fair

You won’t be able to bypass this clause. If you can’t or don’t want to build on the property, someone else will be happy. I understand that this passage unsettles you because you might not have expected it. What I don’t understand is why you’re now worrying about some details if you want to build anyway? Or what do you think could happen within 4 years that would prevent you from putting up a house?

The goal is of course to build on the property and to live there. But it could be that I get the ultimate job offer "months after signing the contract" where I would have to consider a move or a change of location. The clause is not a dealbreaker for me now either. I just wanted to understand it correctly and check whether this is usual and how high my "risk" is. But I see that as 10% of the price of the property (twice property transfer tax at 5% each).

The financing clause ensures that the municipality does not put any obstacles in your way regarding financing, since the bank with sum x, which depends on the loan, is given priority.

The property would be paid 100% with equity and without bank/financing. Therefore, the clause is actually negligible for me, right?

It was just the 20% interest that made me suspicious.