Can't seem to find the following:

dlc065 - Fredman's Midsummer Epistles
dlc100 - Imperator Unit Pack
dlc107 - Leviathan Unit Pack
dlc108 - North America Music
dlc109 - South East Asia Music

I think "dlc065 - Fredman's Midsummer Epistles" is the same as "dlc064 - Fredman's Epistles". Even if you can get them as two DLCs in some way on some store, they will have the same songs.

The imperator unit pack was a limited time offer for steam users who connected their steam account with their paradox account and owned both imperator rome and europa universalis IV. It has been discontinued more than one year ago. AFAIK you can't buy it on any store. I have had conflicting information if it is available in the DLC subscription in steam or not.

The other three DLCs are part of the Leviathan Content Pack and this seems to be missing on GOG. Maybe it would be better if you ask the paradox support about it or post a bugreport on the eu4 bugreports forum at the paradox website.

Thanks for this, I noticed GOG had 107 instead of Steams 110 and couldn't pin it down.
It's strange though, can't find the Leviathan Content Pack on steam either (and I definitely have the missing 3 pieces there), nor any news about what happened to it...

EDIT - Did a bit more digging around, the Leviathan Content Pack was never a separate purchase and should just come with Leviathan when owned. Also jumped in the game to check if 108 & 109 had been re-integrated into the main expansion. It's happened in the past with a couple of free DLC's they did like Women In History, the songs are definitely not in the jukebox though.

I've passed this info over to the manager of the GOG stream team so she can feed it back to GOG, hopefully we can get this resolved!

You are right. The leviathan content pack should come with leviathan. I missed that line when I looked it up on the wiki. I'm relatively sure that I only bought leviathan on steam and I only have leviathan in the DLC list in the steam client, but I have the 3 DLCs from the content pack in the launcher and as separate subfolders in the dlc folder and I have the songs American Soil, Cautious Preparation, Signs of Victory, Discoveries Revelead, Undisclosed Tacticts and Undiscovered Territory in the music player.

I've send a request to PDX and asked them if they might consider a Imperator Unit Pack DLC release on GOG.

Not sure what pack they are in but they are definitely in the GOG version.

Ok. They may well be, but it’s strange that there’s a message in the UI telling me that these two unit packs are recommended when I already have both installed. Either it’s a UI bug(?) or my game doesn’t recognize the DLCs. Both the Evangelical and Catholic unit packs are available for free, as separate packs, but they’re also included in the ultimate unit pack.

Edit:

My confusion has come to an end. I have both the Catholic and Evangelical Unit packs. What I didn’t know initially was that the missing units are in the free MAJORS Catholic and Evangelical packs. I have now downloaded both of these so all is well.

So are we are missing some content on GOG version ?