Yes, any of the alternatives so far ("of Manumission", "of Emancipation", "of Freedom") would work for me -- I don't mind obscure words; they add flavour, and I think that rewarding people that do go to the dictionary (or even knows the word outright) is a good thing. (Those that don't care can still hover over the item, read the explanation, and keep playing.)
It also ties in with the world-building: I'd expect a "Writ of Manumission" to have been around since almost forever (ancient tradition? elves?), while a "Writ of Freedom" would be a fairly recent thing (Rousseu Republic?).
Of course, Maverik gets to decide how classical/modern to be in the wording.