Instead of using a partial, Cusdis comment form can be inserted with this shortcode:
{{- /* Comments with cusdis.com */ -}}
{{ if .Site.Params.CommentsCusdisID }}
<div id="cusdis_thread" data-host="https://cusdis.com"
data-app-id="{{ .Site.Params.CommentsCusdisID }}"
data-page-id="{{ .Page.File.UniqueID }}"
data-page-url="{{ .Page.Permalink }}"
data-page-title="{{ .Page.Title }}">
</div>
<script defer src="https://cusdis.com/js/widget/lang/fr.js"></script>
<script async defer src="https://cusdis.com/js/cusdis.es.js"></script>
{{end}}
{{- /* Comments area end */ -}}
All credits to jmooring