Buy the item that gives XP for crucible and ask the owner of the bow to change the tree before mirror.

this is what i concern.  swap back and forth on one node is what i want

I believe Sushi tested it and you can still finish a tree’s experience after mirroring. Unsure if you can change the tree or swap back and forth on one node though.

No - the premise of mirrored is it cannot be altered. That applies to any aspect of an item

let say if I mirrored an item with the originally choosed 5th node"rain of arrow and toxic rain .......". There is another 5th node option available like" trigger lvl 20 tornado...". am I able to switch between them even it was an mirrored item?

can I Change crucible passives with a mirrored item