Benign, the Gemara barely quotes Targum Unkelos. Nor does it quote Reb Yosef’s Targum, even though it mentions the fact that he made one, and his preoccupation with Targum.
Targum Unkelos is what is Misinai, which is why it has that great status.
The Rikanti is after the Ramban, so you aren’t really adding much by saying that someone after the Ramban quotes it too.
The Ramban calls it Targum Yerushalmi (IIRC). He acually quoted the Nusach Yerushalmi.
There is nothing wrong with a Targum that came from Eretz Yisroel at some point during the Rishonim. It might be very ancient, or it might be from the Geonim, like many other Medrashim are. (Bamidbar Rabba mentions Islam’s claim to the Torah.)
There is no Mesora about having a Targum Yonasan. It is simply printed in the Chumash and when you read it you assume that to be the case. Being that it has many Drashos that show up in the Gemara or other Medrashim it gives the feeling of a compilation rather than something from before Rebbe Akiva Vachaveirav.
It would be interesting to trace the first time it showed up with that title. I’m sure somebody out there devoted months to this.