結論
augroup fcitx5_integration
  autocmd!
  " autocmd InsertEnter * :call system('fcitx5-remote -o')
  autocmd InsertLeave * :call system('fcitx5-remote -c')
augroup END
環境
- neovim 0.10.1
- fcitx5 5.1.10
augroup fcitx5_integration
  autocmd!
  " autocmd InsertEnter * :call system('fcitx5-remote -o')
  autocmd InsertLeave * :call system('fcitx5-remote -c')
augroup END