Neat corners can be achieved with a router - a woodtech would be happy to help with this.
The planer thicknesser should only be used with a woodtech - it’s actually a very dangerous tool, particularly older ones like ours.
The bigger problem you have here is that I beleive ours is still out of commission (another problem with having an older machine).
@Jonty_Bottomley may be able to give an update, as I’m not going to be down there for a couple of weeks I’m afraid.
Principle risk is loss of fingers/hands via planer blades. The thicknesser is safer but still has an entrapment risk… And yes, the planer can kickback and launch things at you if in extreme cases.
I appreciate YouTube makes it look simple, but it’s not the case!