Hi @Dmitry
It is good that you are looking for a solution to have the pre-sets 1-10 on the IR Remote Control.
I am not a developer; just a user with a dangerous amount of information 
In theory such a modification is actually simpler than you suggest (I am totally ignoring the effort from Software Engineers to implement it).
Firstly did you know that Presets 1-10 can be populated with other things than radio stations ? examples are NAS Drive playlist, Spotify Playlist, Amazon Music Playlist, USB Drive Playlist etc.
So for your idea of Preset + 1 or Preset -1 with << >> actually works with the command set preset. For example in httpapi this is the command MCUKeyShortClick:n where n is the integer value 1 -10 (Pre-set Number).
So there is no need for a conditional statement (If in RADIO-NETWORK Mode) as the pre-set command will always take priority.
Check out this topic Control Knob Project where we did demonstrate the function you are suggesting BUT with a separate piece of hardware NOT the IR Remote Control 
Hope the information is useful, Kevin