Diacritics in Field key

Updating Status to: Cannot Reproduce

abá_a and ab_a are the same? Why áíé etc are converted to _ and not to aie?

The field KEY only allows alphanumerics and underscore. It does not retain special characters - they are stripped automatically and on purpose. It is a programming key - it is not shown to users (typically, unless you specifically do that for some reason) and does not need to allow international characters in it.

We do not transliterate the characters either. It's all done in javascript and there's absolutely zero reason to get all fancy and try to convert Greek, Russian, Romanian, Arabian and Chinese characters to some sort of western equivalent.

Really, what you are seeing there is purely a nicety for ease of use for the vast majority of our clients. In previous versions, the field was simply a text input field where you defined the key yourself. Now, it automatically sets the key to a cleaned version of the title - if that doesn't work for you, hit "change" and manually specify it as you did in the past.