Two things.  To let engine read your new tag in template (so that no error pops up), you need to edit the schema at the beginning of formation.js. To let the bonus really happen, you need to modify a few js, and you must understand the whole unit AI attack flow.

So, exactly—since I plan to submit this mod for the next release, I’m currently updating it to the development version (I’m using the Alpha 29 dev build via Snap). If you want to test the Alpha 28 version of the mod, you can download (Releases 0.28.0) that older version from GitHub, though it won't include the latest updates.  

Yes it does, but in the videos, this opposite force is just not applied as it should, so the effect is less then its supposed to be.

Very cool development! I think the application for eles will have a positive impact on gameplay. Often the damage output for eles ends up being less than it could be due to its path being blocked by own (my skill issues) and enemy units. Maybe its negligible, but do the pikemen in video 2 impart an equal and opposite force to the ele that would slow it down? I could see this as a way to nerf it if people think its too hard to impede eles' movement.

Just downloaded you mod and tried it, it said in the mod.json file it was for 0.29.0, is that right? Then I changed it to 0.28.0, and I clicked start new match, and got this: