Okay, no offense to OP, but using the sen-xanadu tools, I disassembled what changes were made and you kind of messed up, OP. You modified the t_text.tbl directly in a hex editor, I think, and it's impossible to decompile it to json using the tools. Additionally, you repacked text.pkg and left a backup file of t_text there, so your IPS patch actually contains copyrighted content.
Regardless, since I used strings to extract your changes, I'll describe the shop fix here:
The 'Purchase %d %s for', 'Sell %d %s for', and other related strings with format specifiers have different parameter orders in japanese: these format strings need the first two arguments swapped and a slight text restructure to accomodate (OP used 'Buy %s\nQty: %d') If the order isn't changed, it interprets the quantity of items as a string pointer, and well...let's just say that dereferences a very low memory address leading to a crash.
As for other unrelated issues: The japanese font differs fron the US font in metrics. You can use the US font instead. Unpack fonts.pkg, and rename font_us.itf to font.itf, then repack fonts.pkg. It works far better.