Hi Milkerman.
I will try to answer your question :).
Yes, you can use it in other tools and engines.
Since the sets and animations are adapted to the RPG Maker mv/mz frame as for tilesets (768x768) and so on. The tool would have to support that frame. But there is also a possibility that it will work without a problem since they are props that are only given to that frame. Another possibility is that you save each prop separately and then put it into a new frame supported by the engine you want to put it into.
Try downloading one of the mini sets I have for free and test it to see if it works.Just for test.
The only restrictions I have are:
I ALLOW :COMMERCIAL USE
I ALLOW: MODIFICATION FOR YOUR OWN PROJECT (GAME, VIDEO, PRESENTATION AND OTHERS).
I DO NOT ALLOW: SELL /RESALE MY PACK WITHOUT MY CONSENT IN ORIGINAL OR MODIFIED CONDITION.
I hope this is a sufficient answer, if you have any other questions, don't hesitate to ask.