Let's say I'm a less than 1k rep user and I edit a question. Does the +2 rep. I get, count for the tags. Similar for tag wiki edits.
Since you need +5 on a tag to "Suggest a (tag) synonym" (and 2500 rep at all).
The "+5" on a tag to Suggest synonym is for you to have earned five upvotes from asking or answering questions with that tag attached.
So no, putting the tag on someone else's question (which you didn't answer) or editing the tag-wiki will not in anyway affect the count for being able to suggest a synonym.