Looking for a font 5x5 and switched to a 4x5

I think you need an image that's a tile of bitmaps.

Also worth checking out http://www.espruino.com/Font+Converter for working from Web fonts, although it's only really tested with the Google fonts (PRs welcome ;).

At some point, given it's 5x5 you may decide it's easier to make it yourself. It's actually not that painful:

var fontBitmap = Graphics.createImage(`

11111
1   1
1   1
11111


11111



111 1 
1 1 1
1 1 1
1 111

1 1 1
1 1 1
1 1 1
11111`.substr(1)).buffer;

g.setFontCustom(fontBitmap, '0'.charCodeAt(), 5, 5);

g.drawString("0123 3210");

Once you have fontBitmap you can do btoa(fontBitmap) to get the base64 and can turn it into a font module