Question about artillery projectiles

I'm trying to figure out how to properly parametrise artillery projectiles. Unfortunately, the help text on the mod tools doesn't really help. It also appears as if most of the parameters there have no effect on artillery trajectory, which makes it even more difficult and confusing.

When I parameterise artillery, I expect consistency. This means:
- Shots centered around the target of interest
- Elevation not screwing up with accuracy
- Predictable firing angles (e.g., if you stick an ISG next to a wall it will fire at 89 degrees angle, which is useless)
- (Ideally) if a shot cannot be delivered properly, I'd rather have projectiles collide with something than try impossible angles

Here is what I have discovered so far:
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What I don't understand so far:
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There are 2 artillery projectile types I want to fix in particular:

1. KV2

https://www.coh2.org/topic/61465/eastern-front-armies-revamp/post/617758

This one seems to be messed up due to elevation. For KV2/Sturmtiger, I can salvage it by setting non-collide and putting low-angle values

2. ISG/Pack Howitzer

This one is trickier. Try it for yourself:
- Park an ISG next to a building and start barraging. The angles produced will be insanely high (even if you try to limit them)
- At the same time, the projectiles will consistently undershoot

Is there a way to fix ISG/Pack Howitzer such that:
- The angles picked are relatively high-angle (45-65)
- You don't have "accidental" high-angle slots