Both only just added to the game in the last 3 patches.
Most nations are using even older than that.
2A6 is one tank. Leclerc was already a powerful tank before, but was let down mostly by the fact it had no backup. Now we have a second that situation has improved and there is no need at all for the S.2 to have better ammo right now when the S.1 by itself was already strong and the ammo is still one of the best shells in game.
If the situation calls for new ammo, it will be considered. But right now, there is no need at all.
Lots of top tanks don't have their maximum possible ammo.
Leclerc was already on par with most nations tanks and was actually ahead of a few too.
There is no need for this shell at all at the moment.