There is no calibration or setting of the end points possible. You can assign a servo to the channels 13 to 16 but the settings is always -100 / 0 / +100!
The reason is that the ROYAL (like the mc3000/4000) is to old for the new software and there are limits as far as the electronic-board is concerned.
Only the ProfiTX is designed to give full access to all channels. The late COCKPIT SX is so far only designed to enable 12 channels - I don't know if a 16-channel version ist possible.
As far as the ROAYL SX ist concerned I don't give it a long future. I own one myself and it works well and I like it. But to all gadgets we buy and use for years there will be an end and we have to have a look what will come next.