Who doesn't look at the Mirror Mirror while Changeling outfits

[Takeru]

Apart from "The Man Trap" where she's talking fluently in another language (Swahili) to someone, also speaks it readily in "The Changeling", et cetera,

Speaking two languages is not a talent or in any way, shape of form special.

she also repaired and rerouted electronics equipment (in "Who Mourns for Adonis") - where Spock indicated she was the only person who could do this,

She was not the only person who could do this, come on. But that she could repair it doesn't mean she wasn't usually portrayed as a secretary, that they occasionally showed her doing other things doesn't really change that.

 

[F. King Daniel]

It is TV, and since when we see Uhura next and she seems like the same exact person prior to her experience with Nomad, it is a convenience that makes sense.

Nah, 23rd century schooling is just THAT good.

 

[Kor]

...
Only 2 universes, ours and Mirrorland? (again, 1960s and balancing nuance with general audiences...).
...

TOS had already dealt with other universes, such as the antimatter universe in The Alternative Factor, and Spock's description of the stone donut as "a gateway to other times and dimensions" in COTEOF.

Kor