Eudora address-book misimported: all original grouping lost, all collapsed into one big list.
That one big list in many cases lacked "Display Name", and many other fields that were present in the original Eudora address lists. Many of the fields were garbled; I had that one big list exported, and found in the CSV file bits of Eudora s field markers, along with redundant LFs (this is under Windows, Thunderbird 31.5.0).
I uninstalled Thunderbird, skipped the full importing, and had it one by one import this and that, but the address books I had it import from CSV files that I made from the Eudora lists (I long ago for other reasons wrote scripts for that).
Alla svar (2)
Import imports per address book, not per list. But I am pretty sure you have observed that already. Unfortunately there is no standard for an address book, or what it will contain. The closest you will find is carddav so import processes rarely work in a seamless manner.
I doubt anyone is going to look at Eudora import this many years after the program ceased to be developed or supported. Those that are going to migrate should already have done so.
Eudora OSE was released almost 5 years ago (September 2010) and was already using an obsolete version version of Thunderbird upon release.
All my e-mail addresses in 21 email-address files were imported into one big Thunderbird "address book", the fields therin not always accurate copies of the originals: sometimes part of the Eudora field-markers (field names between "<" and colon) also showed up, and spurious LFs (this is Windows Vista).
As for migrating, we had to because Eudora s support of SSL was not up to the documentation, not because we wanted any other features that Thunderbird had and Eudora lacked. Lack of UTF-8 support was the only other problem, only once of any importance. I would rather have stuck with Eudora.