So I went to look at the staggering list of monsters that this game will have for your mad scientist to tame, and I will say that they are interesting, thought out creatures that would work great as mobs in a horror TTRPG that you players could try to get away from or fight. Yes, they could work as pets of a player mad scientist they're certainly horrific enough for such a concept.
The thing is from what I've been able to read about the world this game takes place in your character isn't seen as a bad guy the organisation that inflicts "sanity" on you is. From the description on the kickstarter page it sounds like you're playing a mad scientist strait out of an 80s Saturday morning cartoon with Franken Pokemon, but I've read some of the bios of these monsters and they're anything but.
Really I want to know more about the type of character you'd be playing. There are a lot of RPGs where you play what would normally be seen as the "bad guy" or "monster", any thing in OWOD could count. A game where you play the evil scientist bent on world domination with your monster creations could be fun, but I don't see Bogleech passing off this game like this. It's more like you have dangerous pets.
Take the
Lester a monster that was made to infiltrate human settlements and "monitor their most natural, wild behavioral patterns from discrete observation points and harvest unattended, clearly unwanted juveniles for tissue samples."
Or it's female counter part the
Lesley. If you really want a titty monster here it is I guess.
And my personal favorite (not really) the
Pestquirm a baby zombie head filled with worms that was made by at best two zombies trying to fuck, or at worst a zombie trying to get it on with a human willing or other wise.
Again these would be great monsters to fight in a horror game, have the players try to avoid them and fight them off looking for a safe place to sleep for the night, but we know how Bogleech is about creepy things. Even if it's a horrid
monster that causes people to eat until they die through mind control, or an
abomination that shits out it's own eye in self defense, it's really just misunderstood and looking for love.
Edit: Just saw this old comment under the devil bird pic

No it's still insane even if it's based on scientific facts.