You can forma it a fifth time if you want to max [Fetch] but I personally leave it at rank 4 because that's good enough for me and I kinda don't wanna waste anymore forma on a kavat that's already good.
[Hunter Recovery] is there because it regens health for the warframe when your kavat hits someone and that's where maul comes in.
Your kavat is not a DPS tool; it's a really good shield/potion.
The synth mods are used for your reload and making sure your kavat has enough armor so they don't get dunked on by Noxs. You can change out [Fetch] for [Swipe] so you kavat can hit 4 more people and then you can get better chances of that [Synth Deconstruct] proccing. I usually run it without [Swipe] because [Inaros], lol.
If you wanna change out some mods for [Swipe], medi pet kit, and some other stuff then go ahead but make sure those vasca mods stay on. They give free life insurance.