Every time I see a green 'critical' dice roll my eyes alight, only to have my heart broken when I hover over the result and see it's really just a 4 on a 1d4 expertise roll. The pain of this critical disappointment compelled me to finally google how to make a character sheet in Roll20 so I could fix this myself. There may be a better way but this is the solution I found, modifying the default roll templates a bit:
var setroll = "&{template:default} !?{Stat|Intelligence, "+intel+"|Strength, "+str+"|Constitution, "+con+"|Dexterity, "+dex+"|Wisdom, "+wis+"|Charisma, "+cha+"} ?{IncludeSpecialty|No, "+exdice+"|Yes, "+specdice+" } {{name=Arcana ("+specialty+") Roll}}{{roll=[["+diceroll+"+?{Stat}+"+finalbonus+"+?{IncludeSpecialty}]]}}";;
with
var setroll = "&{template:default} !?{Stat|Intelligence, "+intel+"|Strength, "+str+"|Constitution, "+con+"|Dexterity, "+dex+"|Wisdom, "+wis+"|Charisma, "+cha+"} ?{IncludeSpecialty|No, "+exdice+"|Yes, "+specdice+" } {{name=Arcana ("+specialty+") Roll}}{{roll=[["+diceroll+"+?{Stat}+"+finalbonus+"+[[?{IncludeSpecialty}cf<0cs>101]]]]}}";;
The 'cf<0cs>101' just sets the crit range so it never effects the specialty die. The extra double brackets around the specialty section are there to hide the '
cf<0cs>101' when you hover over the dice result. Unfortunately this also hides the actual size (1d4, 1d6) of the expertise die on the tooltip, so this isn't quite there yet. Edit: Added it into the description, not ideal, but playable enough.
Here's the modified file if the sheet the author or anyone else wants to try it. All the skills required a similar modification.