How to check for targeted animal age and upon its death spawn a baby version of custom entity in its place?

Hello everyone. Been trying to replicate vanilla zombie villager infection mechanic for my custom zombie cow in MCreator 2021.1 for Forge 1.12.2. Been trying to make zombie cows turn baby cows into baby zombie cows upon killing them, and adults in to adults correspondingly. I've used zombie entity base for AI and goals so it already preruns with a baby variant for the zombie cow. I just need to understand how to make it check for the cow's NBT tag data and summon a "IsBaby: 1" zombie cow instead. Already made a basic procedure for "When this entity kills another one" trigger, but need your help here.

Edit: Also if anyone knows how to randomise sound pitch, lets say make it 0.8-1.2, please let me know.
Edit edit: Also I'm trying to make it so the process nullifies the cow drop when it's being killed by the zombie cow. Help on this subjects would be very appreciated. It's hard learning this stuff from scratch.