Yeah, 57mm is a decent caliber, but it is bad for a sniping tank and for penetrating more armored parts of tanks.
It's role was a temp thing for the save till I thought of a better thing, and it's gun is actually pretty good for a 57mm. the ammo is a wrap around kinda of thing, so "Anti crew death" is a 50/50 for the gunner/commander, and a 70/30 for the driver. (First number is chance of survival, second is chance of un-survival.)
I'm assuming thin armor and an autoloader due to it being a tankette + a 57mm cannon
I'd say it isn't too over engineered, it matches general modern designs pretty well. Although I don't really think you can have blowout panels with that thin of armor and an autoloading system like that.
I'd recommend something like the 2S25 Sprut-SD, the tankette seems better for infantry support or close quarters combat.
***Sniping tanks need to be fast, have a long range (and maybe powerful) gun, and probably decent ammo capacity. Also, relative to the target, they cannot flank quickly because they are far away, so it's better to have a bigger gun with more penetration so that you can actually do stuff to heavily armored vehicles, which is especially relevant in the IW. Most MBTs have guns sizes from like 100-130mm, which allow them to operate at longer ranges+more pen
**means shell has less damage, range, and can't have as much propellant I really hope it's an autoloaded/clip/belt fed thing cause 57mm is small.compared to most MBT sizes, smaller calibers are used for SPAA and IFVs where it's better to use explosive rounds rather than stuff with high penetration due to fighting planes/infantry
*seems better used for recon or close quarters, mostly phased out after the inter-war period
Why would you use a TANKETTE* with a SMALL GUN** as a SNIPER***?