You could replace the term "subspace" with a real word in the paragraph about the initial intermix issues during flight testing. Subspace is too generic and stinks of lazy handwavium.
By 2285, Excelsior was mostly finished, slightly ahead of schedule. She was launched on thruster power for her initial space-worthiness testing with an ASDB flight test crew. Initial test results were complete, and all ship systems passed Level Four review tests on the Earth-Jupiter run, except for transwarp drive. The transwarp intermix chamber was brought to full power, but there were unusual electromagnetic and thermal fluctuations being detected in the magnetic constriction assemblies. These fluctuations had not appeared during ground testing on Mars, they seemed to be unique to this particular iteration of chamber design. Morrow, Tokogawa, and Wesley were privately unnerved by this, but publicly remained optimistic, and hoped that given more time the ship’s initial transwarp difficulties would be ironed out. Prior test ship flights with the transwarp engine design had proved no more successful, but still the ambitious individuals largely responsible for the project's momentum pushed onward. Excelsior returned to dry dock for final fitting out, including thermocoat painting and striping, to be followed by her commissioning ceremony.
"Subspace" and "Particle Of The Day" ruined technobabble during Voyager's run. I try to avoid using it in my babbles during RPG sessions and when I work as an "engineering consultant" on fan-works like these.
Of course it's just a suggestion... I'm liking the direction you are taking this so far.