NOTE: I do NOT have an installable package created so the instructions below are for some future date.
This is the first JS project I've ever done so I have no idea about JS ecosystem and how to construct installers for it. I just manually copied files to the Coc extensions folder and it seems to work.
extension to for languagetool_languageserver
:CocInstall coc-ltls
nmap <silent> <C-l> <Plug>(coc-coc-ltls-keymap)
:CocList demo_list
MIT
This extension is built with create-coc-extension