There seems to be quite a few definitions that
say eg "surname mi", thus giving away the answer when writing.

Would it be possible for someone to go through with a (semi)automatic search and fix these all at once to just say "a surname" instead?

I am puzzled as I have thought the opposite!

When writing (as in writing the character) for names I don't know what to write if I don't know what the name is. For entries such as "Wang Peng (a personal name)" I can scratch down 王朋. However if I am prompted with "a personal name", or "a surname" I must first click on the pinyin to see what the name is, then write it. This is a minor inconvenience and occurs only for a few names anyway. I have not found the occasion to want definitions the way you suggest, all labeled "a surname" or "a personal name".

How on earth are you to know what character to write then...?

Pictures would be great for learning names

I meant the ones where there is some other meaning to go along with the surname.

If its only a surname, then sure, it needs to still be there.

If it's not a common surname, then most of the time that we include a surname tag at all is when the other meaning of the character is not common, either. So the idea of including "surname X" instead of "surname" is that we're not expecting people to be able to key off the other definitions.

In 麋's case, though, "elk; moose" seem solid enough (although I don't know about "river bank"), so I'll remove the "Mi" from that.