My theories so far are:
1) a misspelling of Alienor (a known Middle-Ages female name, see Alienor of Aquitaine)
2) a variant of the above
3) a misspelling of Elaine
Which do you think is true? I thought for a long time that it was an error on the part of the Polish translator, but then I saw original cast for "Pillars of the Earth" TV series and realized the name was Aliena in the original too.