So... yesterday had the final on-site meeting. A very friendly and, in my opinion, extremely competent advisor worked with me once again to adjust the financing. We are now using less equity but have an even lower interest rate (actually impossible).
This is how it looks now:
Financing need as above (208k purchase price, 27k incidental costs, 100k modernization, renovation)
Equity 70,000
Loan 265,000
Fixed interest period 15 years at 1.28%
Repayment 4.83%
Special repayment 5% per year, also possible in multiple payments per year, always at least 1000€. Theoretically, we could make 13 special repayments of 1000 each per year.
12 months interest waiver period (was important to us so that we can manage the renovation well).
So far, I am completely impressed with the bank and hope that it continues this way.