Matilda will do fine as a Char B1 stand-in, it's as tough and just as slow
Either that or the Grant, due to its two-turret setup. The Cruiser however would be a poor substitute for either S35 or H35/38/39, it's too fast and especially far too lightly armoured, plus for a H35/H38 its gun is simply too good. Stuart might be a closer match, but it's also too fast.
But probably there will be significant GERMAN BIAS either way since the 50mm variants of Pz3 we have in-game just missed the campaign (either missed altogether, or alternatively, 40 made it to the service but saw little to no combat).
Might be that we'll also see Bren as FM24/29, .30 cal as Hotchkiss MG, K98k as MAS36 (five-round clip, durr).