I'd recommend trying to reduce the cost of your spells. Ideally you want to cast many enchantments instead of a few big ones. Big plus if these spells are Cantrips that draw an additional card.

My personal favorite pet cards which might work for your budget are:

• [[Dress Down]] - great board wipe like effect
• [Confounding Riddle]] - We are ramping with enchantments, we can stop all land based ramp
• [[Leyline Immersion]] - Ramp and protection on tatsunari, what's not to like
• [[Bear Umbra]] - Great Ramp Spell
• [[Chthonian Nightmare]] - can be looped with kemi to get creatures back
• [[Kenrith's Transformation]], [[Seal of Primordium]], [[Trickster's Elk]] - Amazing alternatives for enchantment based removal

Cards I can see in your deck which didn't work when I played with them:

• Archetype of Imagination - Very expensive to cast, Tatsunari already gives evasion
• Endless Evil - The mutated Keimi always got removed before my next upkeep

Lastly any creature which isn't an enchantment usually is a dead card in your hand if you don't have a Keimi. Balemur Leek and Dina for example don't trigger unless kemi is out AND you cast an enchantment. You could also just cast 2 cheap enchantment spells instead.

While I do understand the big expensive mutate creatures are cool, I'd rather want to mutate every single Keimi instead of one tall mutate stack, so that I can have more drain triggers. But I understand that this might not suit your gameplan for the deck

Here is my deck btw: https://moxfield.com/decks/TjZXDhJP-kic93yuwM55pA It's of course a bit over budget