Some bugs but they should be easily fixable.
First you xml is referring to the incorrect lua file (instance_select.lua and not instance.lua)
Also the code assumes three levels of instances, and if you already have an instance selected it gets messed up. You can walk up and down the tree of instances without having to select first but it required a bit of work.
You may want to look at the NextY command as it might make things simpler.
Lastly, should probably update the Copyright since this isn't a copy or derivative work and technically does not require attribution.
Great work though.
ok fix some bugs
I am sorry, but can you teach me how to import to the ma3 and use it?
on usb key :
Unzip the xml and lua files onto a USB stick in the \grandMA3\shared\resource\lib_plugins folder.
Edit a new Plugin Pool item, Tap Import, Select your USB Stick at the top Right and choose the XML File. If you want it to work after you restart the console you have to export the plugin to the internal drive.