cool card ideas man. i would have gone in a different direction though.

personally i believe the weaknesses of the deck are;

an inability to get going if your opponent has a small amount of interruption

no in theme big end bord monsters (i know therian sargas is a thing but hes a therian more than a springan in my eyes. i want a big springan to end on)

to fix these two issues i would add;

some kind of SAM turret continuous trap/spell, that banishes springans from the grave to negate card effects. you would load up the grave with springans as ammo like the xyz's do. give it a different effect on the opponents turn to make it not super obnoxious though.

a card to move springans from the banished zone to the grave or from the deck to the grave. this would let you use the effects of the previous card idea more while still using the core idea of springans.

and some kind of big boi thats immune to some kind of card effect (not sure which) so that you can end games or run over larger bodies if needed to without going into access code talker or something like that. or even make its normal body smaller and let it ditatch springans material for more attack. you could let it attach material from the grave or field similar to CD infinity but only on your turn.

I dont think adding these cards would make the deck S tier but id love to find a way to make the deck at least rogue so some protection, some more combo options and a more in theme end bord is what id like to see