If the practice ammunition would be modeled as having the same quality steel as normal AP shells, you can have at least one historical AP-round with 16mm pen. Not the highest pen, but with a fast reload and good knowledge of weakpoints on WW1 tanks, you could be a real threat.
*Only if it gets the APCR and preferably Brandt shells.
This tank’s cannon had very poor anti-armour capability - a few mm, nothing more. Almost any other vehicle would one-shot it. The initial 37mm AP shell was mediocre. The Renault FT was more like a mobile, vulnerable and rapid-firing grenade launcher for killing the unarmoured crews of machine gun nests and foxholes - against steel tank armour at any range beyond point-blank, it’d probably be more or less useless. It’d need to have the APCR (or preferably the Brandt shells) to be approaching competitive - it’d never be truly competitive even then, due to low crew count and armour.
I…think so? Info has been hard for me to find. Honestly, on the shorter 37mm cannon variant, the increase in armour penetration may be negligible, even before factoring in Gaijin’s APCR performance nerf.