So I don't see why Lemon should be here at all.
Beeps said she hated her second body, and she couldn't cope and just switched to a third and it was a perfect fit.
Its probably good for the store to reduce "returns" and resolve user issues before they walk out of the store in a body that is not suited for them.
Maybe its also a new problem with body integration that they didn't encounter until recently. I assume body switching on robots that have upgraded or changed careers (server to embodied) is a recent thing and the occurance of "body integration" with robots who remain in a single chasis for a long time, which is creating a unique incompatibility problem thats not easily detectable or resolved.
Or Roko asked Lemon to be there, cause she herself didn't want May to have an issues with body transfer May is already beating herself up with guilt and been through a lot in less than 24 hours. (which is 7 weeks of the comic btw)
The first possibility doesn't seem likely to me, because from what we've seen previously in the comic that process would normally play out over days or weeks, not in a few minutes. It would make sense to offer it as an after-sale service, but it's not going to be something that gets resolved before they leave the store.
The second one seems reasonable, although as Beast_Reborn pointed out, it probably shouldn't then be Lemon doing that job.
I can't envision the third one at all. If Roko was behind it, I'm pretty sure she would have been asking for
anyone but Lemon.
Lemon is pretty much the Beepatrice of body image counselling - lots of good intentions but awful at the actual job. (I'm sure she does a lot better with the nuclear reactors and dark matter detectors.) While Roko doesn't dislike her, there's no way she'd recommend her to anyone else experiencing body image issues.