[EliRivers]

someone who is looking through new ideas and suggesting that we try experiments to improve our quality, time to delivery, or the other things our team finds important

So someone who is interested in different software engineering and organization practices? Not the same software engineering and organization practices as the rest of the team?

It sounds like you don't want a culture fit so much as you have a culture in mind that doesn't fit, and you don't want that one. Different culture fine, except from a particular range of damaging cultures.

I would suggest that the very fact this thread (and others nearby) exist indicate that "culture fit" really isn't a good term, given how much extra definition is required.