If N.4 didn’t work, then you can’t (or maybe with a custom script to bypass it) change IDs in the string values, you have the change the IDs in the “Animate” local scripts so when you are in testing mode and in-game, the IDs you put in the local script will apply to the default Animations, replacing them.
Also, be sure to have the local script in your custom character’s model and completely named “Animate” so it can prevent the original “Animate” with the default animations to generate as @Wizard_player1001 explained, otherwise it will appear in your custom character and the default animations will still play.
I hope it will fix the issue!