You can try to tweak this mod's velocity and gravity option values to get acceptable results (for reference, the default crossbow bolt's velocity is 3500 in multiplayer games, 2500 in singleplayer, 1500 when fired underwater).
Getting perfect prediction results should not in general be possible because of fundamental differences in the movement code between the default bolt and this mod's.

The best solution would be to ask the prediction mod's author to add support for this addon (difficult, as this addon is not that popular). If that author is not interested, then post here again and I can work to add a prediction option myself (was planning to do it eventually anyway).

Alright, have done that in advance. I think I got a response
Thanks for helping me to the extend you can.

As there have been no news regarding bolt prediction (after several months), I'll assume that its author is not interested in adding support for this addon.

Since I stated before that I was planning to eventually implement the feature myself, I'll be doing just that: an extra option for this addon that will show a preview of the crossbow shots.