okay lets go over your points and go over how each of those could also be transmasciline!
a fully feminine jax is implied to be what is behind this door that is never opened. this is because jax is repressed.
a fully feminine jax could easily just be a pre transitioned jax. alot of transmasc people come to terms with accepting their feminine side throughout transitioning. i know i was one.
2. if jax was transmasc, the "egg" would have already been cracked.
I have seen stealth or closeted transmasc people call themselves eggs. also, the egg comment doesnt have to be a trans allagory. it could simply be a way to explain that jax doesnt want people to break down they're walls.
3. the bow scene where jax confesses to have told her mother something deeply personal and she was hit with personal, degrading insults. and ribbit allows jax to express her femininity and shows support by putting the bow on her. the trauma from her mother's transphobic reaction is what leads to her repressing everything deeply, ditching ribbit, and driving them to abstraction. if jax had told her mother she was transmasculine, the bow would have been dysphoria inducing and a transphobic action.
many parents of transmasc individuals are told they're 'not manly enough' even after comming out. many people also hold masculinity over a transmascs head to take advantage of them. once again, many transmasc individuals have had or do accept their feminine side, ribbit giving jax a bow doesnt autimaticly make it transphobic.
4. her phobia of being outed as transfem. she covers her flat chest and crotch specifically, implying those are parts of herself she hates.
this could very easily be the same for opposite reasons. it could also simply mean SA, body dysmorphia (it isnt exclusive to trans people), ect.
5. jax hates her body. she does not like being masculine.
once again, could be the opposite. jax hates being percieved as 'feminine' or weak and vulnerable. bunnies and overalls are often seen as feminine or childish things
6. if jax was transmasc, implying she is not masculine would be transandrophobia.
it wouldnt. i myself am not very masculine, calling myself that wouldnt be transandrophobia. also, there is a term that is similar to phantom limbs calls trans phantoms, basically referring to the vivid, sensory, and sometimes erotic bodily sensations of gendered body parts that a transgender person was not born with
7. jax is severely overreacting in this scene. this is because she does not like that she feels comfortable in this dress. you can see her body language change and she is genuinely good at wearing one, lifting the skirt when needed and becoming gradually more relaxed in it.
jax overreacting could very well be gender dysphoria. lifting the skirt when needed may be muscle memory. and once again many trans men come to terms over time with being feminine, therefore jax being more relaxed in it would be them coming to terms with being masculine AND feminine
8. jax does not like her name. if she was transmasc, the name would be liked and a cause of joy.
names are not chosen in the circus. i doubt any of the characters like they're name. and jax wasnt liking the adventure anyway, jax prolly didnt care enough to write it down because they didnt care about the adventure at all.
9. we have "isn't she lovely?", which is a song about the birth of a baby girl recontextualised to be about the birth of her transgender identity.
songs do not apply to gender. many people use feminine songs for masculine characters
10. she goes by her deadname (leeroy mateo) because she is not out as transfem publically due to her mother's behaviour, and she frequents riley's bar — a space explicitly for queer people to feel comfortable as themselves. she is likely openly transfem when she is there.
at the end of the show we see that the characters in the circus are not the same as the characters out of the circus, with pomni choosing to go by pomni instead of Abigale. also, in no way did the show state this, and i havent seen gooseworx say it either.