For "How to Ask", I think the current behavior of
[ask] is absolutely correct. The link references a specific page with that specific title, so title casing is absolutely appropriate. Additionally, the current behavior of
[help] isn't quite right, in my opinion, as it is both a proper noun and title, both of which suggest it should be displayed as "Help Center" and not "help center" as it does now. Using
[Help] (with the upper case H) does get you halfway there by displaying "Help center", but that isn't quite right either.
That being said, there are use cases where you just want to link to the page by using the phrase a bit more organically in a sentence, such as the example you provided, "Please consider learning how to ask", but I think that referencing the specific page via title is more common so I don't think all lower case should be the default behavior.
As Qantas points out, the casing of the displayed text is somewhat case sensitive for some magic links based on how you capitalize the text within the brackets, but doesn't work for all of the magic links (
[ask] is one that apparently does not recognize how you capitalize the letters within the brackets), so there is some support already to allow users to decide how they want to display it.
Jan's suggestion seems to be the best compromise and allow everyone to decide how to best apply it:
[ask] should translate to how to ask
[ASK] should translate to "How to Ask" (and I believe the quotes should be included since it is a title and not a proper noun)
[help] should translate to help (I left "center" off because I don't think it makes sense in lower case).
[HELP] should translate to Help Center (no quotes this time since it is a proper noun)
[ANSWER] should translate to "How to Answer"
[answer] should translate to how to answer
(feel free to add others that you think might have use cases with both upper, lower, and title casing that don't currently have that behavior)