There's been talk about how various characters appeal to Japan or the US; and even talk of how Terry might have come out to appeal to various SNK fans in Latin and South America.
Has there been a potential character discussed for having appeal to Western Europe with any consensus, or is that region too diverse with its interests and/or too difficult to really get a read on?
It can be rather difficult to generalize EU for the very reason you said (many, many countries with different sociocultural identities and histories etc.). That said the EU is often counted as one region within the video game sphere due to similar video game regulations and the EU playerbase often playing each other. Generally the EU playerbase does look somewhat similar to the NA playerbase - although there are important differences:
Consoles arrived later to the scene than in the US - meaning that EU audiences are not generally as familiar with NES games as the NA / JP fanbases. In consoles' place, computers became more prominent - particularily
the Amiga in the UK and Germany. Companies like Ubisoft and DICE first started out in the computing business, and the insanely-big LAN party DreamHack was born out of a friend circle playing computer games.
Wolfenstein,
DOOM and their successor
Quake have major legacies - especially here where I live - and those helped build DreamHack's momentum. Computer games like
Half-Life (and
especially Counter-Strike) would add more fuel to it and the wider computer playerbase in EU.
The computer game sphere wasn't just shooters - RTSes like
StarCraft / WarCraft III and
Age of Empires had solid playerbases too (and some of the former would later translate to
WoW and
Dota / LoL), and it didn't take long until more genres got going to a lesser extent. The
Sims has also consistently been a big deal amongst the more casual crowd, with the huge number of expansions being noted.
It was this environment that would later spawn
Minecraft.
Still, just because computers were more prominent it didn't mean that consoles were completely left in the dust during this period. Sure, games like the FF series (up to VII) and SMRPG were not released in the region initially - but Rareware (formerly Ultimate Play the Game)
made the initial move towards the Famicom / NES because they believed that the ZX Spectrum (then-dominant in the UK) didn't have much of a future. As far as consoles went, AFAIK the UK actually leaned towards SEGA during its Master System / Mega Drive (Genesis) heyday. While the SNES had a foothold in Europe, Nintendo started to streghen itself in the region during the N64 days... but you know the drill. The PlayStation
Crashed (heh) the party here too (Ubisoft likewise made the shift to consoles and got going with
Rayman). And the Xbox later on went on to establish itself pretty well within the EU.
Still, the initial
Pokemon craze was probably the point where Nintendo had fully established itself in the region.
Super Mario 64, OoT and
Lylat Wars (Star Fox 64, there was just a copyright SNAFU with it and Starwing- I mean, Star Fox SNES) had already done quite a lot, but
Pokemon helped solidify Nintendo's presence. Since then, EU has generally looked quite a lot like NA, with smaller variations of course based on country and console. Western EU does constitute the majority of Nintendo sales within the EU at large. I'm not sure by how much, but the UK / France / Spain / Germany are the main four countries IIRC. Other countries like Italy, Portugal, BeNeLux, the Nordics, etc. also have sizeable Nintendo (and console) fanbases.
As a small sidenote: You know how well Madden sells in the US for example?
FIFA has that spot here - although the
NHL games sell well in countries where hockey's popular. A significant minority of the PlayStation and Xbox sales are FIFA buyers. And a major reason why is because EA was quick and included many of the big (and even smaller) European leagues and national teams in the FIFA games. They even started including second division (and even lower) leagues and teams quickly because those teams generally have long histories and very invested fanbases too. Football is that ingrained in the general European culture. It's gotten to the point where EA often partners with local big clubs and sell limited club-themed versions of the game.
I've also heard that Layton has a significant following, and I can certainly see why: Layton is comparable to not just Sherlock, but also Franco-Belgian comics like Tintin. I haven't found anything to outright confirm the latter, but given that Satoru Iwata - back in 2009 -
speculated about the reason why Layton's popular in Europe I wouldn't be too surprised. Tintin and Layton does have somewhat similar themes, such as a focus on adventure and mysteries.
Zhuge did retweet a particular snapshot of Nintendo's sales in France (back in 2019):
There was a problem fetching the tweet
As far as the mobile side of things go... haven't looked into that, albeit I'd imagine that EU would be rather similar to NA there too.
Eastern EU / Russia can be somewhat of a different matter (Russia's gaming population in particular leans heavily towards the computer and free / cheap downloads, with the PlayStation being the console of choice), but that's not the topic.