What if it's a "Lossy Encoder" for 15th-Century Latin?

[Mauro]

The idea of a lossy encoding has already been proposed in different flavours, mainly because it can lower the characters entropies and create 'words' with a regular structure. I think @quimqu proposed a ciphering method with a many-to-one substitution scheme where part of the entropy was transferred to ancillary 'residuals' which were necessary to fully decode the text (there's a thread somewhere here, sorry for not providing the link, I can't find it now).

For myself, I think a possibility is a (inherently lossy) many-to-many substitution scheme, which might possibly lower the character entropies, create words with regular structure and have few repetitions, given the -to-many substitutions, as observed in the VMS. But the hard part is getting this (or any other) scheme to work.