No sound with custom trees.

Trees = mineable rock chunks.

It's all working fine with the rock chunks model replacing the tree model and the units will mine it.
But I can't get the units to make any sound as they mine it. Not even the default "axe wood chop" sound will work.

Can anyone please help?

I can't tell you what's wrong, but the first idea that comes to mind is triggering the sound if it's really important to you.

I believe there's an event for "destructible takes damage". Use that event under the condition "destructible-type of triggering destructible equal to *custom tree*".

If you imported a sound for use, then use the "play sound" action and use your imported file. If not, you'll have to find it in the Sound Editor, then right-click and click on "use sound" to extract it.

Hopefully this is accurate and helpful.

There doesn't seem to be an event like that.

To my knowledge, the sound effect is called from the tree model while playing its harvested animation. You will need to modify the rock chunk's model.

I dunno how, but I got the Axe Medium Chop sound to work. Which actually sounds fine with the rocks.

New question, how can I remove the hero level up animation/sound?

you probably need to change the harvesting unit's attack stats. The field would be:
Combat - Attack 1 - Weapon Sound

change it to whatever works.