I don't exactly know what you are asking or how to do it, but I believe I can' point you in the right direction.
You should look into creating or customizing an OSC pattern config file rather than assigning from the action list.
OSC config files for reaper are text files that you can edit with a "plain text" editor. They are stored in the REAPER application folder underneath OSC. The Default.ReaperOSC file located in that folder has information on creating your own.
Take a look at this:
https://www.youtube.com/watch?v=Z2QoJzDWVuw
Downloads for the TouchOSC template and Reaper config file are in the video description. Rather than starting from scratch I used this template as a starting point to make my own.
You will definitely need to do a little reading and messing around to get this to work, but I feel like probably you could get it to do what you want.