Perhaps this post does something for your character problem:
/t/2785/1
Edit: there has been a discussion in the German part of the forum:
/t/12440/1
And quite honestly: it is a completely different if you say
Er machte Löcher
or
Er machte Locher.
So I would live with the short-comings of these players and write them a fierce letter about their incompetence.
Getting from the reduced set of characters back to the full one is almost impossible.