Adding a skill via traits on the actor page, on the class page, or on the state page (possibly also via traits on weapons and armour, but I haven't tested these) doesn't seem to add the skill to the character or class's available cards. The only things that seem to add cards properly are adding the skill via the class Learnable Skills section in the database, via the Change Skill event command, or via the Effect 'Learn Skill', for Skills.
Also, it looks like only skills in the first skill category ('Cards' in the sample project) are manageable in the deck screen or accessible in battle, even if a particular actor or class has access to those extra skill types. Scrolling to the other skill types in the deck screen shows an odd section of transparency that persists even after scrolling back to the main Cards category, and I don't think skills from any other types show up in battle (I was trying to make a skill add a card that was only usable by specific actors, via being a skill type only certain actors have). Weird bit circled in red here:
Also, you don't seem to be able to select other cards via the cursor, in battle (I haven't checked the deck menu, yet). Clicking selects the current card in battle but you can't change what you have selected by clicking anywhere (or anything short of using the keyboard, or possibly a gamepad).
If any of these should be feature requests, let me know and I'll move them to that thread instead.