The cheat codes in heap I've posted above work for the first vacation after an exit and restart of the game. So exit the game after every vacation - and they basically always work.
if the game crashes, and you are on atmosphere - just press and hold L on the next start, and the cheats will deactivate.
ONLY activate them again, once you are with a girl, on the island. And NOT on the title screen. Otherwise savegame corruption might occur.
Only use three (max zack dollars player, max zack dollars one girl, max satisfaction one girl) at one time, to minimize issues occuring. I've posted how to edit this file on the switch _very_ quickly in the cheats thread, a few postings after this one:
https://gbatemp.net/goto/post?id=8562824#post-8562824 .
Back up your savegames once in a while, just in case.
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Apart from that, the codes should be safe to use. Its pleasent to have the girls always at max satisfaction and always accepting whatever gift you throw at them (because of max (9999999) satisfaction).
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Tested the item replace codes, they work.
There is some weirdness with the cheated suits, if you first put them into your closet and take them out again. (??? on liked, closet showing them as not owned), but it seems to have gone away, after one more put into closet, take out of closet cicle, or after some time... Owner paradise modes also list them, so everything should be fine.