I read up to vol 4 on Novelbin in English. The rest I used Google translate on booktoki. https://booktoki469.com/novel/6673670?stx=인투+더+로즈+가든&book=완결소설&spage=1
Yeah. I read the 3rd timeline, thinking maybe Kloff would grovel and regret, and actually appreciate Aeroc. Nope. It felt like he got everything handed to him on a silver platter. EVERYONE around Aeroc kept pushing Aeroc to Kloff. Even his butler was like Aeroc feels more alive around Kloff. Made me want to throw up. Aeroc never gave Kloff a hard time either. Kloff just steps into his personal space a little, and Aeroc gets all flustered. Just when Aeroc grows a bit of a backbone, Kloff tries to commit suicide, fails, and Aeroc spends the rest of his life with Kloff. Kloff pretends to have amnesia so that he can be with Aeroc. I was like what a manipulative asshole.

So I binged read the novel last night.
How I interpret the timelines and the different versions of them is that OGAeroc gets transported into 2nd timeline and lives happily with 2ndKloff that adores him. He gets his happy ending.
OGKloff dies and transports into 3rd timeline with a new, 3rdAeroc. By the end of 3rd timeline, Kloff is miserable bc he can never be with the Aeroc he wants. He can never tell /his/ Aeroc he loves him. In his attempt to make up for the pain he caused his Aeroc, he plans to completely devote himself to the 3rdAeroc.
So the only "punishment" OGKloff got is that he can't be with the Aeroc he wants. I HATED OG Kloff in 3rd timeline too. He basically manipulated everything to get to Aeroc, and in the end, he's using Aeroc as a substitute for the Aeroc he tortured and killed. I hate that he got his happy ending.