your questions regarding the game rules (improving the interpretation).

Misclicks are a player issue, not a rules issue. Just like knowing the order of attacks when moving onto a cell that borders two guards simultaneously.

With this rule in a Dark game, I would fly behind the Hive (if there was a cell there), and I wouldn't attack between the Djinns and Sylvans, but as soon as the hero is in a safe place (one single cell), it seems like you can't attack. I would fly in and aim the cursor (there's no need to force players to know which monster will be attacked first when there are multiple monsters - the rules should be simplified, not made more complex).