These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
The "Marked One bears the Guide's child" thing doesn't seem to account for the possibility of a female Guide. Obviously a female Guide won't bear the Marked One's child because that messes with the Anvilicious symbolism, so one can only assume that in a world where men can be impregnated without the slightest trace of a justification then a woman can somehow impregnate another woman or a man. Or the author hadn't considered the possibility of a female Guide, which shades into Unfortunate Implications.
Gary Stu: Richard shows early signs of this, including developing magic abnormally quickly.
Mary Sue: Millicent (saintly Woobie with Prophetic Dreams) is a Purity Sue and Serena (offspring of canon characters, who walks, talks and uses controlled wandless magic before she's even a year old and becomes an Animagus aged two) is a God-Mode Sue in training.
Then there's the sexism, for instance the whole (implied) no female Guides thing and the fact that when Ron and Hermione join Harry to confront Single it's suggested that Hermione be the one to stay behind to look after the kids. That the author is a woman doesn't make the Unfortunate Implications any less so.