In the character sheet, the ability skills are not correctly displayed.
I have a screenshot but I don't see a way to upload it here, so I'll just explain:
- under INT, there is Nature, which has a score of +0, shown as "-"
- if the character wears Arcane Circlet, it grants a +1 in Nature
=> "Nature -" is still displayed, but if I hover the mouse, I see: "Nature, Intelligence Skill, 1d20+1", whereas it was 1d20 without wearing the circlet.

So ability skills may be taken into account in the checks, not sure, but they are not displayed correctly.