Modding asset use PSA
If you’re looking to use assets originating from other people’s modding projects for the creation of a variation, even when only for personal use, your safest bet is to always ask permission first. I’d advise doing this, even when a modder’s permission rules state making a personal variation is fine without asking first. It’s incredibly polite and will be appreciated.
Most modders won’t mind you taking their assets and making a personal variation at all, but if they run into them online they are often left wondering whether it is a case of theft or not. This forces them to track the source. Because mod theft is a real thing, it’s just best to give modders a heads up and avoid any and all confusion.
Obviously if you are looking to publicly release a mod using other people’s assets, not asking beforehand is largely considered theft. Bottom line, always ask first =)