Kommo-o-4 now has Draco Meteor instead of Shell Smash.
And I also noticed in your calculator, Hawlucha-4 doesn't hold any item. It's supposed to holding Power Herb.

Source: SciresM tweet

When entering in your own set, you might see attacks suddenly dealing about 4 times as much damage as they should if you don't correct this one field. Given the specialization of this fork, it seems like the most common use case is for the custom Pokemon you enter to be intended as level 50, rather than 100, and that should be the value it's initially populated with.

There seemed to be an issue involving Z-Endeavor in the showdown calculator that maybe hasn't been fixed here? I can't get the all-v-one or one-v-all pages to work. Also, those pages seem to be missing the terrain options.

I honestly don't know how to better debug or describe this. See this screenshot comparing the mainline vs this calculator's output for Surf from a Starmie against a Blaziken:

I noticed this because Psychic somehow deals more damage, which makes no sense given the lower base power and the fact that both moves are STAB.