Also, if it helps to think about it this way...the character sheet isn't calling attributes, it's creating them. So, the sheet is feeding the Attributes and Abilities tab for the Attributes. You can then create abilities that reference the attributes. The character sheet can implement buttons that do the same thing as abilities but doesn't create an ability, but you can create an ability that references the roll button on the character sheet. When creating a roll button, you use the same commands as you would if you were creating an ability...in fact sometimes I will create the ability and copy/paste it into the value of the roll button—that way I make sure the formula works before creating the button. If you have a multi-line formula, that's OK. Here's a multi-line formula I just put into a roll button today, in fact: value='/em Rolls Physique! 
/r [[{1d0+2,1d0+[[@{physique}+?{Modifier|0}]]}kh1]]d6sd 
/em Remember the modifier was ?{Modifier|0}, so apply [[ {1d0,1d0-2+@{physique}+?{Modifier|0}}kl1 ]] to the face value of the highest pair...' The first line is the /em statement. The 
 is a new line character. The /r is the beginning of the second line, and the second /em is the beginning of the third line.