Setting up Vim autocompletion: issues with getting Neovim compatibility layer working

I’ve spent the past hour trying to get Vim to offer autocompletions for Julia code. Here is my vimrc so far: .vimrc · GitHub. I’ve tried following Vim and Neovim · julia-vscode/LanguageServer.jl Wiki · GitHub, although it quickly became apparent it was really only written for Neovim, as on Vim the editor complained that neovim_rpc command was not found. So, to remedy that I added the roxma/vim-hug-neovim-rpc plugin, again with Plug and after tinkering with its Python settings I manage to get :python3 import neovim to finally run successfully, but now when I start Vim I briefly see this error:

(which, in case you cannot see it, is:

Error detected while processing function neovim_rpc#_on_stderr[4]..<SNR>109_on_core_channel_error:
line	1:
Traceback (most recent call last):^@  File "/home/fusion809/.vim/plugged/nvim-completion-manager/pythonx/cm_start.py, line 10, in <module>^@	from cm import getLogger, start_and_run_channel^@  File "/data/.vim/plugged/nvim-completion-manager/pythonx/cm.py, line151^@	self.nvim.call('cm#complete', name, ctx, startcol, matches, refresh, async=True)^@

). I’ve searched the issues of the nvim-completion-manager and vim-huge-neovim-rpc repos for a match and found none and I’m wondering whether this is my own set up that is at fault (my OS is Arch Linux, if relevant) or whether this is a bug and where, if this is a bug, I should report it. I also know that now nvim-completion-manager is now deprecated and I’m just getting more and more confused. I decided to alter my vimrc to .vimrc · GitHub and with it things seemed a little better, as now I receive no errors and I see:

It does not offer and completion suggestions after I type the . after Pkg (with suggestions I was expecting being add, clone, rm, etc.) and I must admit I’m not sure what I’m meant to do with the completion I’m given, like how I’m meant to tell Vim to use the selected completion.

Hi there, vim user here as well (not neovim). I opened up an issue a while back related to this

https://github.com/JuliaEditorSupport/LanguageServer.jl/issues/265

This is what I have in my .vimrc for this using supertab completion manager,

However, I currently have it commented out and didn’t experiment with it much.