Question: There have been a lot of edits up for review recently that consist of just adding the syntax highlighting tags to code snippets.

Is the general consensus that this would be considered 'too minor' and therefore rejected, or is it seen as a good edit to make snippets language-specific for syntax highlighting. I am on the fence as to whether to accept these edits or not.

Answer: 
When reviewing I personally would not reject it if there truly was nothing else to correct. But I don't think it should be the only thing you change if the post has other issues. In that case I would either go for a "too minor" vote, or make the required changes myself, removing the "helpful" checkmark.
Proper formatting of code blocks and correct syntax highlighting can improve a question immensely, so YES you should accept those edits - especially if it requires the use of a [language hint](https://meta.stackexchange.com/a/22189/146015) to correctly identify the syntax highlighting to use.