For me, it is not at all understandable how such a question about securing financing can arise, not at all. These are crucial questions that I clarify in advance with the respective bank when applying for financing.
Above all, why to the checking account? And just asking, which bank transfers 50,000 euros for services from the construction contract blindly to the checking account? I simply cannot believe that, which bank takes this risk? Around 10,000 euros - 15,000 euros to the account when own contributions are planned at the time of application to buy materials, okay, but definitely not 50,000 euros! Which bank does something like that???
Invoice issuance, send it to the bank and then have it transferred by the bank. A certain amount for material purchase for own contribution to the account, provided everyone proves the use and then possibly requests a new tranche, but certainly no craftsman or trade invoices from the work contract to the account! I transfer smaller craft invoices from the tranche myself and the larger ones from 1,000 euros by the bank.
By the way, the fact that money is needed from the loan does not necessarily indicate whether equity capital was available or not, because this must be used first.
Has it already been paid by us?? Do you have any additional equity capital besides that which was considered in the financing concept?