Edit transaction amount in save file for internal transfer

I really need #1673260 wish: internal transfer with different currency.
As a test I created Internal transfer transaction to random account, then manually edited save file. I found destination "ope" line, edited account id, then changed target currency amount. Also I changed dst_account id in source ope. This seems to work... Sure I can't edit this transaction in Homebank, but it's not a problem. Can you think of some side effects that I can be missing? I kind of afraid to messing up my save file.