Restrict a role to administer certain vocabularies and terms, and remove the access to creating vocabularies As far as we all know Drupal (still in D8) has a lot of issues with permissions and taxonomies.

So I give my user role the permission to Administer vocabularies and terms so he/she be able to access the page at admin/structure/taxonomy but then I want to restrict that role to certain vocabularies (then Vocabulary Permissions Per Role module comes in handy)

The only issue that remains is the Add Vocabulary permission that comes with Administer vocabularies and terms

So here's the question: How can I restrict the user from Creating new vocabulary / Editing existing vocabularies while giving access to maintain other vocabularies taxonomy terms?
"Creating a new vocabulary" is what you do using the URL admin/structure/taxonomy/add, while "Editing existing vocabularies" (say with machine name demotags) is done using the URL admin/structure/taxonomy/demotags/edit.

A possible solution to "restrict" access to these URLs (which seems to be the missing piece you are looking for) is to use the Rules module for this. To do so, have a look at my answer to the question "How to make the permissions of a module more granular?". It includes a rule (in rules export format), which you should be able to use if you apply these minor tunings to it:


Check the Rules Condition about which roles this validation should be applied for (if any, if not remove that condition).
Adapt the Rules Condition with the URLs containing visitors (to match the taxonomy related URLs like in my first paragraph).
You probably don't need the Rules Condition with the "regex" in it (you only have a few URLs to be validated). In that case, you don't need the "OR" part either.
Review the Rules Action (the message you want to show, and the redirect you want to force).