Hey, I'm glad you like it! So I did a bit of digging, the indexes you need should match the decimal codes listed for the Latin-1 supplement characters found here: (https://en.wikipedia.org/wiki/List_of_Unicode_characters#Latin-1_Supplement)
For example, the character range you're after for the accented characters I think would start from the À character (192), and end at the ÿ character (255). The codes for Latin Extended-A should also all match characters in the font.
To more directly match them up, you can head here, the webtool that I use to make the font: (https://www.pentacom.jp/pentacom/bitfontmaker2/). It has an import functionality in the top right, where you can upload the ttf version of the font. Then, on the toolbar of the left-side pane (the font creation grid), click the button in the topright that looks like a document with input and output arrows to the side, this should bring up the "Data import/export" window, which will both display and let you download a json structure that maps the decimal codes to an array of the pixel data. A bit more difficult to actually line up, as you would have to determine the index of the character in the character map on the right of the screen first to be able to determine the line number matching the decimal code you need. But that shouldn't be necessary except for any extraneous characters I might have missed, as from what I checked, the data output matches the decimal codes listed in the linked wiki page.
Hope that helps and best of luck with the project.