100%, but ideologically she’s every bit as much a Jedi as Luke is here. He’s not had any formal induction to an organization, so that can’t be what Yoda means here.

Yoda is also shown quite clearly regretting the kind of stagnation he allowed in the Jedi Order, which is exactly the reason Ahsoka was put in the hard situation she was. The Clone Wars very much set up her character as an emblem to show the rot that allowed Palpatine to rise, which Yoda acknowledges and regrets quite explicitly there. It’s not a ridiculous inference to assume he respects her and would validate Ahsoka as part of the “good side”, which is about all “Jedi” can mean in this context. She even explicitly and repeatedly tries to turn Darth Vader.

Anyway, I do agree in that it’s not a massive plot hole or anything, but I’d say that if we’re ever explicitly shown Yoda meeting Ahsoka pre-Empire, this scene will be weird.

They’ve done a surprisingly good job of maintaining this scene, actually.

Rebels: Kanan is dead by now, and Ezra would be lost in deep space at this point. Yoda also wouldn’t know about either.

Mara Jade: 100% still a Sith Assassin right now. Also not Disney canon or anyone Yoda would hear about.

Ahsoka: This is the best candidate, since Yoda would know about her, and likely regret the decisions that forced her to leave the Jedi Council, making it weird to dispute her status as “Jedi”. The most favourable assumption is that he assumes she’s dead.

All said, remarkable protection of an Episode 5 made before episodes 1, 2, 3, multiple TV shows, novels, and sequels.

Twins can be very close, especially as a kid with no concept of twins or sense to pick out distinctive details.

My father has a twin brother who lives far away, with the most obvious difference between them that my father generally keeps a beard. One night, when my Dad shaved and came to tuck me into bed, he was met with an “Uncle so and so, when did you get here?”.

Of course now as an adult, I’d be able to tell them apart no problem, even if they did dress and style the same. I’ve observed their mannerisms and minor cosmetic marks with a keener eye as an adult. But as a young kid who couldn’t even clearly tell his own father from his twin, I find a kid being unable to recognize a chance encounter he wasn’t expecting very believable.