Just a few minutes ago, I used that tool for the first time, and it worked as desired - and made me add a title for the newly converted question. Looked OK.
Of course the new question had no answers yet. So I converted an existing comment (with dependent nested comments) into an answer. As usual.
But unfortunately the newly converted answer made it not to the question, and it was also lost as comment. - Oops, lost data, and unfortunately work of others...
A closer look showed a different outcome: The answer is there, but as answer to the original question (so out of context). Here's what the "recent activity" log tells:
Dear administrators, I have two questions:
asked 21 Jan '15, 09:18
Preamble: Anyone with a minimum of 2000 rep point can convert an answer to a question.
"With great power comes great responsibility"
As far as I am concerned it is fine to convert a comment to a question... but you need to think about what you are doing before you do it. I would not go overboard and use it often. A better solution is to suggest to the author that he/she create a new question to raise the profile of the issue.
If you really must convert a comment/answer to a question then it can be done and everything can get carried with it. For example, in the situation that you described you could have first make the comment an answer (if it is not already an answer), then convert the comment (which you wanted as the ultimate answer) to be a comment on the answer (this may be done using two steps: convert comment to answer and then convert that answer to a comment). Be careful when doing these steps because sub-comments (to the comments that you are changing) will be carried along with the comment! Once all of the text that you want to keep together is in one 'bundle' (i.e. under one answer) then you can convert the answer to a question and all of the comments attached to it will be carried along with it. Once the question has been created you can restructure the comments as desired - e.g. convert the comment to an answer.
Re. making the fixes afterwards - yes, anything can be done, but I'm not sure the effort is worth it. I suggest that you write an answer quoting and linking back to the comment.