I don't think I ever had to go to the bank to get a loan, but I'm pretty sure that it not the same procedure as in Bygfoot. Such as in bygfoot, you have a specific duration for the loan (e.g. 12 months), but you cannot give the money back whenever you want: you generally have to pay a fraction (in my previous example: 1/12) of the total loan each month.
The true calculation of loans is indeed very complicated; we should contact some economics experts. I think there are several ways to do that (for instance, reimburse first the interests), and there are several ways to consider the case where you can give you money back before the deadline, or on the contrary, if you have to ask for a extra loan to reimburse the first one.
Anyway, I think it can make bygfoot more realistic if loans were a little bit more lifelike. For instance, you could have to chose 1) the amount of money you want, and 2) the total duration of the loan in weeks. Then, the computer can calculates the interests, and give you 1) the amount of money you have to pay each week, and 2) the total cost of the loan.
In my mind, this feature (which is certainly not very difficult to implement) would make the financial side of bygfoot "smoother". I mean that economics in bygfoot are very "violent" : "you have to give back 500 000 next week". Argh
and it is almost impossible, for instance, to really know if you are earning some money or not: if you have a cup match at home, the balance is misleading for 2 weeks. My dreams for bygfoot 2.0 is to have much more economics graphs, etc. in order to be able to have a "scientific" economics management : what is the evolution of the money corresponding to the tickets, the evolution of the total wages, the ratio between the wages and the average talent of the team, etc. For the moment, you still have to play with your intuition... or with a spreadsheet software opened in the background