> Is it for use in the font sprites of consctruct 3?
Not sure. I don't use Construct 3, so I don't have a lot of experience with their font sprite setup. However, these fonts come in .ttf (true type font) formats, which I don't think is what you use for font sprites. I found this article about how to convert .ttf fonts into sprite fonts, so you can check it out if you wanna do that: https://www.construct.net/en/forum/game-development/tools-and-resources-27/sprit...
> do the letters come out with the accents?
Not sure what you mean. What accents are you talking about?
> is the background transparent?
Since these are .ttf files, yes the backgrounds are technically transparent. It's just the letters & numbers.
Let me know if I can help out more :)