Just like Jaime, I don't think Tyrion was ever aware of how abusive Robert was to Cersei. I feel like when it comes to Tyrion and Cersei's relationship, you have all this inner monologue from Tyrion thinking about how he likes to see her uneasy/scared/miserable and he definitely tries to get that out of her, but he does not actually revel in her suffering once he sees it with his own eyes (which is something that happens to a lot of the characters in the books in general) and is definitely the most empathetic to her out of all her family members (I'd say).
Yes I generally agree with this. I think Tyrion was less aware than Jaime for certain, but not entirely ignorant. He shows no surprise when Cersei speaks in front of him about how Robert knocked Joffrey's teeth out or how she threatened to kill him in his sleep following. The dates aren't provided but Tyrion being aware of the time when Robert's bastard twins were murdered in Casterly Rock seems likely.
That said, the way Tyrion conceptualizes Cersei mimics the dark humor he uses to make light of/cope with his own relationship with his father... he might privately make a quip or twelve yet it doesn't sit well with him nonetheless. Tyrion does show some compassion for Cersei, even tentatively holds open the place she could have occupied in his life, but unfortunately it never goes further than that between them (in fact it gets much worse).
[However I don't want to gloss over the entitlement Tyrion displays when referring to Cersei's sexual life, from jokes like it doesn't seem quite just that you should open your legs for one brother and not the other, to speaking to Lancel about not getting Cersei pregnant as if she wasn't competent enough to know that herself, and so on. That's closer to the point I was originally making]
Jaime though, I think Jaime was pretty aware (a king has no secrets from his kingsguard). Cersei also chooses to wrap Jaime into the general milieu on that point i.e. her being forced to play certain gendered roles on behalf of men in positions of power over/around her
She had played the dutiful daughter, the blushing bride, the pliant wife. She had suffered Robert's drunken groping, Jaime's jealousy, Renly's mockery, Varys with his titters, Stannis endlessly grinding his teeth. She had contended with Jon Arryn, Ned Stark, and her vile, treacherous, murderous dwarf brother, all the while promising herself that one day it would be her turn.
-AFFC, Cersei V
Somehow it's Jaime who is most aware of both his siblings' internal struggles, who serves most closely as their ally, and yet that same Jaime plays an intimate role in perpetuating said struggles.
