This is an old thread, so this idea may have been already supposed:
Instead of having individual tags for content like "Drug usage", have different categories of content rated by the developer out of 5*, similar to how the site Common Sense Media† does it.
Each axis of rating should also have a word-limited textbox to clarify what content is in the game, again much like CSM. Coinciding with this is a list of tags oriented towards potential specific triggers, (e.g: self-harm, eating disorders, flashing lights, sexual harassment).
This should also integrate into a Content Warning Page, appearing when you click on a game for the first time before showing the game page. It would show the content ratings and associated clarifications, as well as the list of trigger tags, then requiring a confirmation to proceed to the game page.‡
*: possibly with an aggregate community rating shown side-by-side
†: who I have significant hang-ups with, but nonetheless
‡: a plausibly important coinciding change is to allow the report system to file for misrepresentative tags and ratings