In part, the user guide says the following regarding One Core Voices:
Windows 10 includes new voices known as "OneCore" or "mobile" voices. Voices
are provided for many languages, and they are more responsive than the
Microsoft voices available using Microsoft Speech API version 5.
I think some or perhaps many people reading the sentence, may draw an
incorrect conclusion. The sentence is correct and it specifies Microsoft
voices. But I think another sentence should be added that other voices,
such as the MSAPI version of Eloquence, are as or more responsive. I don't
know if they are more responsive and someone familiar with both would have
to write the statement accurately.
My point is that, worded as it is, it is easy for people to misunderstand
what is written as applying to all MSAPI5 voices.