Yes: you have to re-do the mod manually.
If you have the textures already extracted, you could try to slap the mod together, but, currently, there's nothing to convert them.
And I doubt that there will ever be something to do that.
Here's a tutorial for UE4 modding.
THE INFORMATION OF THIS TUTORIAL IN THESE FORUMS IS SLIGHTLY OUTDATED. I did a revision to the tutorial in December of 2022. Instead of amending this page, I'll link you to all my tutorials that teach how to do cosmetic mods for BnS. If you are new to BnS modding or even if you were looking to...
www.bnsbuddy.com