The steering wheel controls doesn't work the way you're thinking, the turn signal can't get "crossed"/shorted out with the radio controls because the steering wheel controls are connected separately from the turn signals, the turn signals aren't on the steering wheel they are on the steering column.

The horn, the airbag, the radio control and if equipped phone control are all on the steering wheel and they are all connect by what is called a "clock spring", since the steering wheel goes round and round just a straight wire/s would be broken in short order, so to overcome this issue the "clock spring" was invented, it's a ribbon wire with numerous wires in it that is in a coil like a clock spring inside a plastic housing between the steering wheel and the steering column, all the steering wheel controls, horn, airbag, etc. are connected via the clock spring, as you turn the steering wheel the clock spring coils get either tighter or looser depending on which way you're turning, at some point just the tightening and loosening can stress one or more of the wires in the coiled ribbon and break it or short it out with one of the other wires.

So it seem you need to replace the "clock spring", if you're mechanically incline and with the proper tools you can DIY the clock spring (not really all that hard to do), if so you can surely find a YouTube video of how it's done in a T4R.