In the short-term, you can manually use both an attack and damage adjustment on the weapon you want to make up the difference with.
In the long run, you'll want to find the Community UA file that has the hexblade, and rewrite the script on that class ability to loop through your equipped weapons that don't have the two-handed property. You'll have to remove the dex/str bonuses somehow - then add a bonus based on your charisma bonus. It will obviously have to run post-attribute or later.
If you want the community authors to try and fix it, you'll want to head over to github and open a ticket so it gets on their radar.
Github link:
https://github.com/Sklore/HL_DD_5e_Colab/issues