If they say it can't be done, then the only work-around would be to manually create your own abilities that call the character sheet abilities, and set them as a token action, which is basically what I do. When I'm feeling particularly lazy, I drag the character sheet button onto the macro bar, click that, then press the up button while in the chat box, which will bring up the previous command given; in this case, the character sheet ability you just used. Then you can copy & paste that into the ability you're creating. If you replace your character's name with "selected" (as in "%{Bob the Terrible|Fort-save}" becomes "%{selected|Fort-save}"), then it becomes generic and you can copy that from character to character. The one thing to keep in mind is that you shouldn't name your abilities the same as the name of any character sheet ability; if you do that, Roll20 won't know which one to use when called, and it will cause unpredictable behavior. If you really want to use that name, put "⁠" (without the quotes) somewhere in the name; it won't be visible on the token action button, but it'll keep the names from being the same.