I've heard Rheolydd and it makes sense for an object, but I've never heard Rheolaeth in this context and it seems more suitable for the concept of control rather than for a device. Do people use Rheolaeth for remote control?
Yes, Rheolydd is the proper term for this.
The person who added this word was confused about 'remote control' as a process, ie controlling remotely, which is the real meaning of rheolaeth bell.
This will be altered when we get to revise the course.