@Trin Tragula
In the dev diary post you refer to Votadinia as Pictish, when really they were a British tribe and should be in the same culture group as their southern neighbours. Assuming that reflects an in-game culture difference and isn't just for the sake of the post then it should be changed.
Like the rest of northern Britain we have no sources for the Votadini before the 1st Century AD when they appear on Ptolemy, who is obviously your main source for the region given that the his work is the only source to mention the Damnonii (Gildas probably does in the 5th Century, but it is unclear and gives no location). Since all we can do is extrapolate back using later sources I feel fine to use early medieval material pertaining to the Votadini. By the 5-6th Century the Votadini became known as the Kingdom of Gododdin and at this time they are recorded as being a British kingdom, distinct from the Picts [D. Petts & S. Turner] [D. Rollason]. I've not been able to find any firm archaeological evidence to support the idea of a cultural shift from Pictish to British prior to this and so it is logical to assume the Votadini were always a British tribe and shouldn't be in the Pictish culture group.
Further, as Sally Foster notes, the Romans regarded the Picts as being those people living north of the Forth-Clyde isthmus (see map), further supporting the idea that the Votadini should be in the British culture group. It also suggests that the Damnonii should probably be British as well, especially since the later Kingdom of Strathclyde occupying their lands was a (remarkably resilient) British one. However no-one I know of has been able to firmly link them to the later British kingdoms in the area like they have the Votadini.
So yeah, the Votadini (and maybe the Damnonii too) should belong to the same culture group as their southern, British, neighbours.
A slightly oversized map, which while from a later period than Ptolemy (see the Gaelic in Scotland) neatly
shows the rough border between the 'British' and 'Pictish' regions.
Foster, Sally, 1996, Picts, Gaels and Scots: Early Historic Scotland
Petts. D, Turner. S, 2011, Early Medieval Northumbria: Kingdoms and Communities, AD 450-1100
Rollason, David, 2003, Northumbria, 500- 1000, Creation and Destruction of a Kingdom
Wikimedia (for the map)
TL;DR: Votadini were a British tribe rather than a Pictish one.
Furthermore, Manaw/Isle of Man was likely Brythonic until the Viking age which isn't quite represented on that map.
May be worthwhile making this a dedicated suggestion post so it gets noticed. I for one look forward to playing as the ancestors of Gododdin in Votadinia. It'd break the immersion and stop me playing the faction if all the pops come up as Picts.