FearLess Cheat Engine

I hope that I find someone here who can help me solve my problem. .. used "infinite crystals", I bought two skins and suddenly I have -1,569,265,544 crystals. This cheat does not work repeatedly, restarting the game did not help. I hope to write right here. Someone will understand it.
It was a mistake to try that trainer. I'm afraid I'll lose all my saved positions. Deleted saves problem can solve, but I will lose everything (about xp and the progress of my characters! And I do not want this, of course).
I've been searching for a long time on the internet, some advice, I have not found.
Have you encountered this problem? Can it be solved without loss of progress?
Thanks so much for any answers.

Basically, it's a signed integer and they set it too high; probably set it as an unsigned integer.
But -1,569,265,544 == 0xFFFFFFFFA276E878 so seems like it might be a problem with the trainers code in general.
And there doesn't seem to be a CT here for it. You can make a request for it in the Single Player Cheat Requests section (you just need a pointer or script to set the "crystals" to a good value).

But really you'll want to start backing up your saves before editing memory, or be willing to delete everything and start over.

Why not ask the trainer author? They would be more qualified and interested to answer questions about their own trainer?

You went too high. You'll have to start a new save file. You don't need to go crazy with the zenny / XP -- you can put way beyond what you need without exceeding the 'limit'.