The warnings not being "logical" is of course nonsense, but I actually agree that '5+' is a tad on the obscure side. This is a human-facing message and we can be nicer: either '5 or more' or 'at least 5' would be clearer.

'5-10' is not quite as problematic. 'from 5 to 10' would probably do, and 'between 5 and 10' is better but also worse since it could be misinterpreted as the set {6..9} unless we append ' inclusive'. No strong opinion here.

As a special case, '5-6' is always better written as '5 or 6'.

I've looked through the various contexts where the messages appear and the patch below (which keeps 'X-Y') should be an improvement in all cases. Anyone strongly against?