Hey twilight!

- if I have 15 Parac, I can't mutate any to Paracoxodon
Checked this, and it seems working normal, just curious, in your case, did you level up Paracoxodon skill without level upping the Paracoptera?

- Space Lobster customisation does not work (at least during the Metro Dome bossfight)
Can you elaborate in which scenario? I'm afraid you facing this scenario : the resurrection is instant, and if you got locked in the boss lazer beam that continuously damaging you over time, you will eventually die again after getting resurrected.

- how many summons should this have?
Your calculations are correct, 15 Parac/15 Paracoptera/15 Paracoxodon plus an additional 3 Paracoptera from Acid Blob skill, or unlimited Parac from Paracoxodon death.
Gonna add your different coloured Paracoptera idea to my suggestion note

- Dormant Cloak seems not to work (it would be OP though)
Image attached, its a small shield to cover Vetteris :D

- Vanguard does NOT recharge your Sin.
Found!

Space Lobster: probably that.

for the Paracs: I'll have to reset my progress. I'lm curious anyway how that effects stickers and achievements.