The standard is to use curly single brackets when inside double curly, for everything. I discussed this with Covarr. In fact, straight single and double should only ever be used when you are unsure what the font will be. In books, it should be avoided always.
If you are referring to spaces after the colon and comma, they are added by FF7 because I altered the character spacings. All the quotes I place up here will be the same.
As for Alex, he would also need a LOT of understanding of FF7. I am not sure if he has that, but without it, it is a non starter, and to make it the most competent it could be, he would also need direct contact with the writers.
Part of the reason I feel so confident about a lot of this localisation is because I understand the game back to front. If I didn't understand the game like I do, it would have been near impossible. 500,000 characters also seems a little on the low side. It is around 1.3 MB text, so that would be closer to 1 million inc spaces.