I took a glance at about a dozen builds of Manic Miner games but none of the ones I saw had a different font/character set for some reason.
Given that its possible to change this via a simple poke anyway and the fact there's a large chunk (2480 / #9B0 bytes) of 'usable space' at 37708 / #934C , this seems quite odd.
Note the above is the Bug-Byte version, the S.P and MAD/Venta still have the space but its not got source code remains in, it should be a bit higher up probably 33719 / #83B7 in these versions, but lets ignore those and stick with the B-B one otherwise this will get too confusing. The SP version contains a repeating pattern of 0 / #00 , 255 / #FF to 'fill' this space up.
I did try quite a few months ago to implement this change but despite my efforts at the time I could not get it to sit within a permitted boundary, given how the print routine works. The routine is identical in both JSW and MM so the 'fix' should be the same. The effects usually resulted in corrupted font output (printing graphics or nothing) or in some cases the wrong character by quite a way such as say printing "G" instead of "4" for a random example. I cannot recall exactly what was printed or not. I do recall trying then to manually just insert the font data a few bytes up or down to 'test' it (ignoring any potential crashes) but still got stuck.
In JSW to erm 'redirect' it elsewhere it is simply POKE 38546 / #9692 , x , this instruction is merely LD H , 7 so its the 7 that we would change.
In MM the same code resides at 37579 / #92CB and the instruction is the same LD H , 7 , so the change is POKE 37580 / #92CC , x to replace the 7 with another value.
There is the slight chance of putting the 'font code' elsewhere such as buried in the top third of the graphic data or the middle section however given how the screen memory (and memory in general) it would take a lot of work to 'hide' it there without destroying what was present. The huge gap would be great *if* it could be used, the fact its a shade over 2K in size does make me think this is possible.
Any thoughts ?