No offense but this advice is rather risky and legally dangerous, please don't tell people to potentially put their products in jeopardy by doing this. The correct thing to do is for MongoDB/Elastic to just clarify the wording in the license.
AGPL is okay.
I'm not hiring a lawyer when I'm selecting a few tools to benchmark. I'm not using EC until I've had the license reviewed by a lawyer. Ergo, redis or similar.