With that said, I do want to improve how the Celtic peoples look in CPRplus. Do you have any specific suggestions? You can be creative here - you can indicate which of the clothes or headgear in the Celtic Portrait Pack to keep, how to physically modify the existing hair or beard assets, or which assets from other portrait packs to use instead. Or whether to have two or three portrait sets for cultures in the Celtic culture group, for that matter.
I do not have the files on me, my laptop with ck2 on it no longer chargers, so I'm using a Toshiba tablet/laptop for university at the moment (it's a bloody nightmare).
I would recommend a different culture for the southern scots, if not then a different late game gfx. The Baliols, Stuarts, Bruces and Comyns were all products of the Norman invasion, a rather good essay is written about this in the book
Norman Expansion (Asgater Publishing Ltd, Farnham), ed. Keith J Stringer and Andrew Jotischky. The book is a collection of essays with on the different theatres of Norman expansion, the particular essay I referenced in an essay of my own was called
At the Northern Edge: Alba and its Normans by Alexander Grant. Robin Frame also wrote a top one called
Ireland after 1169: Barriers to Acculturation on an 'English' Edge, but I digress.
I would suggest that the norse christian hair is a tad ridiculous for both the Bretons and Celts, the Celtic Hair is perhaps fine for the Irish (it would actually go quite well for the Saxons imo). For the Scots I would lean towards either using the 'Englishgfx' or perhaps using western beards and celtic hair. The tartan is indeed a modern thing (or early modern as the Jacobites used it... filthy traitors) and should be replaced with English clothes.
I'm not sure on the Historicity of the crowns either, I would imagine that following the norman invasion the Scots used a pretty similar Western crown, prior to that maybe none at all. We know that James V remade the old crown that was commision for James IV's marriage to Margaret Tudor, but that all happened after the scope of this game (if only a little bit after), and this crown is pretty magnificent with Fleur de Lis on it and made in the fashion of the English Crown with obvious reference to the Auld Alliance and Margaret Tudors' Plantaganet mother.
The issue here is that history diverges as soon as the game starts, yet I usually start around 1100, or even with Henry II on the English throne (not having a Plantagenet in England is weird to me) so the Scots have truly felt the effects of Norman integration by then.
To be honest I'd possibly go for different Early and Late portraits, either that or have them split into two different cultures, after all there were two languages spoken in Scotland, the Scots spoken by the violent borderers (my people on my mothers side) and the Scottish spoken by the savage Highlanders (no bias I swear). The only people the borderers hate more than the english are those pesky Highlanders after all.
Perhaps use assets from the French gfx that you have going, to represent the Frankish influence on them later on, if all else fails the standard Western Clothes make more sense late game than the Celtic ones.
The Irish I'm a tad unfamiliar with, as an Englishman who mainly studies English and Scottish history at university I've only looked at Ireland in the context of the various Anglo-Norman invasions (Anglo if you're Irish catholic, Norman if you're Irish protestant), but I imagine they weren't particularly dark ages like in their attire.
Sorry for the ramble, this post wasn't particularly planned, more of a written version of my thought process.