There are front shifters marketed for 2x10 or 3x10 speed setups.
Why should they be only used in combination with a 10 speed rear shifter? Do they have any relevant influence on the rear sprockets, like different gap sizes?
I would like to purchase a 2x10 or 3x10 front shifter and use it on my 3x7 bike, given there are no problems with this combination.