We first met Forge in the future timeline with Bishop in season 1, where he was greying a good bit, and depicted as old or older than Logan(who had not yet been given the extreme backstory yet, and he ages somewhat similar to his peers on the team, as we see by his appearance relative to them in DOFP to begin with), compared to the young and strong Bishop. I think they just kept the same VA when they introduced Forge in the present timeline, in that Iceman/X-Force episode.
So their modern day Forge was being voiced by a guy they cast for sounding like an older guy to begin with. Mark Strange, evidently, who was about 50/51 when they recorded season 1, looks like the Iceman episode came out in 1995.
Forge's age in the comics has always been somewhat unclear. I mean, he was introduced in 1984 as a Vietnam War vet, so he'd have been a decade after his war, let's say he was in his teens or early 20's when he enlisted, deployed a few years later, at best, we're talking maybe 35 years old, a few years younger than Xavier(who was really only like 35/40 then in a brand new cloned body) who was a Korean War vet(back when these dates almost kinda made sense).
So Forge/Banshee/Xavier/Emma were all the same age of 35/40 or so, but the X-Men were like 25ish for Scott/Jean/Angel/Beast/Storm, or younger 20's like Nightcrawler, Iceman, Havok, Polaris, and then there were tons of the teens Piotr/Rogue/Kitty/Rachel/the New Mutants/Jubilee/etc. By the time the 90's were wrapping up, Xavier, Forge and Banshee got interpreted as even older men, while Emma shifted even younger, so much so that by the time the Morrison(who ages Charles precisely at 41) era wraps up, somehow Emma is actually younger than Scott and Jean?! But especially after 60 year old Patrick Steward was cast as Xavier in '99/2000, who now is more "
grandfatherly", not, "fathered a 17 year old(Legion) right out of college during my gap year" old, like he was in the canon.
Anyways, I'm glad to hear a new voice for Forge.... Gil Birmingham, who appears to be an actual native American from Texas, who also has a degree in engineering before getting into acting, so By the Goddess, he's basically Forge incarnate!
Interestingly he's about the same age as Alison, only a few years older than her, which should give their characters good chemistry, and I like that his age is not too drastically greater than Ororo's in this series(despite both voice actors being quite older than their characters are depicted, and actually
older than Forge's VA in TAS, relatively, based on recording date).
(Also interesting to note that Magneto's new VA is much
younger than Rogue's).
Anyways, I'm very curious to see how LifeDeath(and LifeDeathII, even though M'Jnari is already in the TAS canon?) is adapted. I mean, they kinda have to do some version of the Adversary's Fall of the Mutants storyline to give her her powers back in a faithful or at least referential manner, which they have been doing so far with other canon. After how they handled all the Inferno/X-Factor stuff in one episode, I'm confident they found a way, but I look forward to seeing the precise composition they go with.