My own view on the locations is below.
In general, I think that the use of villages, parish churches, small settlements, or similar is better than the use of an area/island name for a location. Such that, for example, "Keinis" is better than Dagö except for one minor fact -- that Hiiumaa is owned by the Teutonic Order in Livonia (which, in my mind, should replace "Livonian Order" as the name of the country) should mean that the location is actually called Pühalepa / Poilep which was the T.O.'s parish on the island.
Also, I think that in the main, the improvements we have seen in this area are really great. However, instead of having a number of roughly equivalent-in-power states as we should, we have the following:
Denmark: 7 locations
B. Tarbatu (Dorpat): 4 locations
B. Osilia (Ösel): 4 locations
B. Courland (Kurland): 2 locations
A. Riga: 8 locations
C. Riga: 1 location
Teutonic Order in Livonia: 31 locations
(Bishops: 18)
Livonia altogether: 57 locations
In reality, the bishops in joint action were often able to at least stalemate the Order, but this doesn't seem likely in this setup. But also, it feels weird to have the Danish properties almost twice as "large" as the chief bishops' territories. So I would like to add one location to each of the bishops' provinces to have four more in Livonia for a relatively minor change which would still alter the balance of power rather a lot (the bishops together would be ~22% stronger). As the Bishop of Tartu was, at least in theory, a bit more powerful than the other bishops based on his lands' population and vassals, it could be an option to add two provinces for him, but perhaps that's too far outside the current options that still exist. Based on that, I have two variations of his lands.
Most importantly, I think a lot more maritime locations are needed to make this coastline feel "good" or decent enough to allow for some maritime warfare that's not completely boring.
Land locations:
1: Keinis belonged to the bishop; the Order's parish on Hiiumaa was
Poulep /
Pühalepa.
2: I would rename this to Carrien / Karja and pass it to the bishop (+1 to B. Osilia)
3: Renamed to either Peude / Pöide (main castle until approx. late 1340's) or Soneburg / Maasilinn (main castle from approx. 1350's to 1560's) in this region. This would stay with the Teutonic Order in Livonia.
1, 2, 3, plus Arensburg would form a four-location province called "Ösel" / "Osilia" (for which the bishop was named).
4: Leal (modified)
5: Werder / Virstu (modified location of current St. Martens), based on a 15th century castle and harbour which was relatively important in the 16th century.
6: Alt-Pernau / Vana-Pärnu added as a second town for B. Osilia, and his main grain export station.
4, 5, 6, plus Hapsal would form a four-location province called "Wiek"/"Maritima".
7 & 8: Modified borders for Tolsburg / Toolse, as Toolse was mainly a harbour/port location so should not be so extensive on the inland side. Main roads would have been through Wesenberg/Rakvere.
9: Removed "Wendau" to replace with Ecks / Äksi, which will be contentious again, but this was a heavily populated area with mostly many small villages/manors, so that's why I would opt for this parish center.
10: Add one to B. Tarbatu with Warbeck / Varbeki which is first mentioned about 50 years after game start, but ended up being a significant castle into the 17th century and ruled the mouth of Emajõgi.
11: Add second to B. Tarbatu with Kirrumpäh / Kirumpää west and north of Neuhausen / Vastseliina. Major castle from 13th century. This is outlined with the yellow line.
12: Modified boundaries for Neuhausen / Vastseliina.
13: Minor boundary modifications, but named to Odenpäh / Otepää as "Walk" was a border settlement and shouldn't be featured in this way.
These provide a slightly larger province that's wholly owned by B. Tarbatu in the beginning of the game.
14: This could be either Salismünde or Lemsal, dependent on where the center was placed, but this is essentially the archbishop's extra location.
15: With some argument, this could be either Roop/Gross-Roop or Lemsal
16: I liked the idea mentioned above of this one being Turaida which was one of the archbishop's most significant locations.
17: Hasenpoth released from "Durbe" and provided as an exclave to the B. Courland.
18: Modified boundaries for Durben.
Sea zones added to allow for 1 (Sõrve Strait, to control access), 2 (Livonian Coast, to allow for access to Riga), 3 (Gulf of Riga, could be considered deep water), 4 (Gulf of Pärnu, for access to Alt-Pernau and Pernau), 5 (Approaches to Osilia and Maritima), 6 (Väinameri, or the Sea of the Advocate of Maasi), 7 (Coast of Maritima), 8 (Coast of Harjumaa/Harrien), and 9 (Coast of Virumaa/Vironia).
The locations otherwise are more or less okay.