Considering how Epic loves devs, I don’t think they will worry about editing things. And that’s exactly why they didn’t say it in their license. You might wanna check this yourself, this is an open source tool from epic for editing DNA(what’s behind metahuman) and import it into maya MetaHuman-DNA-Calibration/LICENSE at main · EpicGames/MetaHuman-DNA-Calibration (github.com). Check clause 2.
As for exporting anims, I’d say it will cause you enough efforts to apply anims to other characters in other softwares. Since Epic would like to generate facial anims using CTRL_expression, which is stored in DNA telling how they will drive bones, so you cannot drive facial bones without it outside Unreal. It is possible to bake anims to pure bone movement that I don’t know how, but it will only apply to metahuman style head armature and lose morph drive. The CTRL_expressions are compatible to ARkit, so in theory you can transfer them to other heads, but if you’re not an experienced technical artist, I’d say it’s a technical attempt rather than license violation. Since you reproduce RigLogic on your own.
That is a bit off topic. Anyway, all you should care about is UE only when sharing. If you managed to successfully export facial anims and following the law strictly, then these anims are part of metahuman as they are using techs under Epic’s copyright.