Written in the appendix was that they had paid “their” reserve funds for independence (T/N: see earlier chapters) in the first place and thus had no further money to spend on “them”. Thus, “them” loaning out the money would be the expected way in this situation. It was a considerably irritating letter.
Besides, the pages were strangely filled with only hiragana and katakana thus was quite difficult to read.
Judging from the handwriting, most likely it was written by the eldest son Kurt.