Your are right considering “for that” as a translation for ça.

The meaning is the same between:

Je te pardonnerai jamais ça. (pronounced either J’te pardonnerai… or Je t’pardonnerai…)

and

Je te le pardonnerai jamais. (pronounced either J’te l’pardonnerai… or Je t’le pardonnerai…)

The first sentence is putting more emphasis on the pronoun. An even more emphatic sentence would be:

Ça, je te le pardonnerai jamais.

Formal/literary/school French would use:

Je ne te pardonnerai jamais cela.

I believe Spanish has very similar constructions:

Nunca te perdonaré eso.

and

Nunca te lo perdonaré.