I've recently took it upon myself to attempt to better my understanding of the Hygromanteia's angelic and demonic names disputes. The Hygromanteia is a grimoire, usually hidden amongst others, that is said to predate works as the Liber Juratus and probably the source for the Key of Solomon. I'm not sure this is true. In fact I doubt it and find it more likely a Greek version of the Key of Solomon, but it is an important text nonetheless and one I have found much use of.
Generally included in the Hygromanteia are a list of angels and demons of each planetary hour and their purposes, these are included in Harleianus, Atheniensis 1265, Gennadianus, Monacensis and Barnardaceus. As a rule of thumb Gennadianus and Monacensis both tend to agree with Harleianus whereas Atheniensis and Bernardaceus usually mirror. I would say there is a fairly good reason for this, as the angels names tend to reflect the hours purpose. For example ion is the angel of the 24th hour of the day of the Sun (before Monday sunrise) and literally comes from the Hebrew word meditate or rest. I believe the word meditate is more suited and rest is a mistranslation although it means both, as the hours are supposed to have purposes and rest makes no sense as a purpose. Anyway, you see Atheniensis 1265 and Bernadaceus are both missing the purpose of the hours. Due to the oddity of an angel being referred to as rest and without the aid of the purpose of the hours Bernadaceus concludes it was a corruption of Ionioniel (Union of God.)
The lack of the hours causes much trouble for the translations of these two texts however Bernadaceus is not to be completely ignored. The manuscript actually aids in many translations as from Harleianus the angels names were already corrupt and got worse. On many respects although the absence of hours is a problem for their translations I have found Bernardaceus and Atheniensis to be mostly the most accurate. Over the next few weeks I shall upload some names of angels and their probable correct titles, including the use of the angels in the Hygromanteia which is talisman based.