Copy /usr/share/kodi/addons/skin.estuary to /storage/.kodi/addons. Then you can edit the xml files.
Is this still valid for Libreelec 10.x ?
It used to work with 9.x, now it does not work, I wonder why.
My changes in "/storage/.kodi/addons/http://skin.estuary.edit/xml" do not affect the screen.