There seems to be a fork of Castra that is in active development called Castra Prime (https://mods.factorio.com/mod/castra-prime). It claims to fix some issues and allows the player more control over the enemy progression.

Xyrc's tweaks doesn't support Castra Prime yet, so it's impossible for now

I did some testing with the castra prime mod. I experimented by adding the current version (0.8.1) to the pack. So far it seems to work fine. I also did some digging into Xyrc's tweaks and the only changes it does is modify the science pack recipe by adding another step with research data similar to some others.
Based on my testing it should be possible to add now?

Check the latest update out! :D

Tanks for the update