is there a possibility to concat strings/variables within the empty text of CA Catalogs Form Designer?
I'm trying to get the user.location.address combined with the user.location.city like this: concat$(_.user.location.address),", ",$(_.user.location.city) or $(_.user.location.address)+", "+$(_.user.location.city)
and this is not working... is there an other way to achieve that?
No, Empty Text is just that (text). You cannot use variables there.
You could use $(_.user.location.address + ', ' + _.user.location.city) in Value. That would give the initial value that the user could override.