This is so minor that I feel stupid for even calling it a bug, but even more stupid for never having noticed it so far:
In the editor, in the skill panel selection, the skill is called "Exploder".
However, when you place a pickup skill and select what type of skill it is supposed to be, the ticking box is still labeled as "Bomber".
Might be somewhat confusing for new users.
If Exploder is the new term, which I do prefer because it's unambiguous and avoids confusion for anyone who has played Lemmings 2, then the pickup skill should also be called that way.