[ordu]

But what about 'Ы'? It looks like 'bl', doen't it? 'Ы' is one codepoint and one glyph, though 'bl' is a sequence of two letters. I believe that the method described will miss such things. Cyrillic also has 'Ю', I suppose it is possible to design a font that make it look like 'lO'? Are there any fonts like this in a wild?

[Sharlin]

Yes, it's one of the things listed in the limitations section.