I haven't read the role reversal AU, so I can't weigh in on that part. But I feel like I want to throw something in about the main story.
I know what you mean that it feels "kinda off". Like it's not quite love. But I've read this story a couple of times and I feel like the progression and individual character arcs lead me to the conclusion that there are a couple key factors regarding this. First, Euihyun's journey is about healing overall. Some of this is by learning to trust, love, rely on people, and generally be vulnerable with your emotions. This is something Taeju not only didn't have to worry about/consider in his own life, but he was able to take advantage of those vulnerabilities/insecurities in other people. And Taeju's arc had to do with a lot of detoxification in regards to how he treats other people and the consequences of those actions. That's why learning to match each other took so long and was and actual PROCESS that had to be worked through. It's also what makes the story feel more rewarding. Throughout the whole story they're each doing a lot of personal growth while also growing closer towards each other and figuring out a dynamic that works for them. But, to my second point, I DON'T think they're in the same place at the end of it. Specifically in regards to their feelings for each other. I think that while they both obviously love each other Taeju is strongly IN love with Euihyun, while Euihyun simply loves him. These, to me at least, are two different levels of emotional intimacy. And, once again, Taeju grew up with the emotional freedom already to recognise and explore these feelings as they come. Euihyun is only just coming to a place where he can recognize and admit what these feeling are, as well as the depth of them. While I think they both have them, I think their emotional pacing is different. Sort of like Taeju holding Euihyun's hand while he takes baby steps into their relationship.
I've putting this off for a while because of the 2 time sa but now I completely read it.
It is not bad I shall say but I like the role reversal au a tausand times more. Because the main story feels kinda off, I mean like is what bottom feels really/completely/purely love? The top is literally his savior(from life, from debt, from abuse,etc.) So I am wondering, maybe it is some kind of a syndrome(like stockolm). But in the AU it is different, nobody owes anything to the other(Because top was able to pay the debt, and just got the debt themself just to be close to bottom)