Main account safety when cheating on alt

I have family share disabled, no computers/accounts authorized for family library sharing. And despite that i still find installed games only from main account in the alt's library. Is that normal? Are there other precautionary measures i must do before starting to cheat on alt? I noticed later that project infinity's free cheat created some files inside the cs go directory, am i forced to reinstall Cs go or closing cs go, steam and restarting pc is enough?