+1 on seksan.
Can try to look at the ppl behind REXKL https://architizer.com/projects/rexkl/
Thinkcity isn't an architecture firm but they work in urban history and restoration so they might have good leads.
YTL is a big conglomerate but look for the people responsible for KLPAC and Sentul West (it's no doubt gentrification but it's worth looking at what they did with the Sentul train depot complex - that's now Sentul Depot).
Apparently Studio Bikin is involved with the APW Bangsar site (which part of it was the New Straits Times printer building) but the ppl behind this building nearby might be a good source of info: https://www.malaymail.com/news/life/2016/09/11/bangsars-striking-new-landmark-is-an-architects-dream-come-true/1200553
There's a lot of small-time and medium-sized firms imo but I'm not surprised online search doesn't yield a lot, compared to the big players above. You guys may be surprised at the extent of the work already done tbh.
ETA: this entire channel is basically a video lookbook of firms doing what you guys are interested in, I suspect: https://youtube.com/@designseedstudio - I especially like the Denai Sepuloh house (apparently old-timer architect), but there's at least a dozen of projects on that channel that might yield leads for you.