Well by taking the burden, honor and responsibility of a 20y Enterprise standard Eclipse will also have to do a bit of standard-setting now, at least in this particular area.
If at least a minimum level of code quality and consistency in the codebase cannot be archieved, why would large enterprises still use Java / Jakarta EE instead of Dropwizard, Spring Boot, Angular or a combination of JS from GitHub that certainly don't care about each other's coding standards or quality?;-)
I strongly suggest, something similar also gets created if not for all of Eclipse then EE4J does something similar. A tiny skeleton exists:
https://wiki.eclipse.org/Coding_Conventions but it merely covers things like license headers now.
The failure to even get TCKs work under a single umbrella or get a proper BOM, Parent POM, etc. at MicroProfile show us how bad it would be for Jakarta EE if those things continue to happen the same way here.
The balance between a reliable Enterprise platform that survives for at least another 2 decades and "Sons of Anarchy" may be hard to find, but it should be found if Jakarta EE still wants to matter. Pivotal and Google may play a very similar role as Oracle does in the current Java EE and Java ecosystem, but both have their projects developed Open Source for most parts and contributors stick to those conventions whether they enforce it via build tools or not.