Seems to me you could have saved yourself a lot of work and you could support a larger input set by using combining accents. For example, "è" can be written as "\N{LATIN SMALL LETTER E WITH GRAVE}" or as "e\N{COMBINING GRAVE ACCENT}". You used the former, but the latter has a stronger parallel to the input text.

You can squish the accents into the first form (when possible) using Unicode::Normalize's NFC.