Post-match analysis.

I would like to know if it's possible to achieve this with fewer losses, and if I did everything correctly?

I'll try to comment.
First, I always place the Gremlins in the middle; I'm not sure why, but I'm just used to it. Otherwise, it's roughly the same: 1 unit next to the Vampires, two next to the Clothiers, 1 leading the Zombies, and the Gremlins calmly shoot down everyone.
Second, you have 3 Golems and 3 Water Elementals; I don't understand why you're saving them. Put them in the second slot and let them fight the Skeletons; it's less of a loss than losing the Gremlins.
In general, I placed: 1 unit - 3 Vampires - 1 unit - Gremlins - 1 unit - 1 unit - 1 unit. The losses were Pixies and Water Elementals, which aren't really needed, and 2 Gremlins (they hit 2 nearly defeated Clothiers).
By the way, is this a save from a real game, or was it generated for the Crypt? If it's from a real game, then I don't understand what the 3 heroes are doing near the Crypt, not on the road. There's plenty to do on the road for the hero – in one turn, they can gain experience for three levels.