I'm worried it may have despawned after my game crashed. I haven't seen it for quite a long time, and although I could just wait for it to get near to me, i'd rather finding out through some command or any other way that doesnt require waiting still, im really far away from the last time ive died to it. Im playing in singleplayer with entity distance in 500%, btw.

What's your coordinates from spawn? The Witherstorm does eventually no longer render if your extremely far out, had this in a world where I was 100k blocks from spawn and couldn't see the storm at all but it was still active.

Not as far as you were, it was about 6k blocks from the spawn (-5715 35 810), but now im pretty much at the spawn. Yet, I can't see the storm nor have seen it on my way. I do feel like ive been finding mobs sick with the wither disease more often than before, though.

You can do/tp @e[type=witherstormmod:wither_storm] @e[type=witherstormmod:wither_storm,limit=1]. If there is a storm it will successfully teleport it to itself and say "teleported wither storm to wither storm". If the storm is despawned or something, it will say "no entity was found"

Thank you so much!!! It seems like it did despawn, indeed, no entity was found.

If you're using optifine and this is singleplayer, make sure "Smooth World" is off to prevent this from reoccurring.