I have a Renanthera storiei, but its just spiking....maybe in a couple of months it will bloom, so the only comparisson I can give you is from IOSPE:
IOSPE PHOTOS
as what I have seen from your pictures: you have a Renanthera storiei.
it is definitely not a R. imschootiana (the lip are totally different)
I understand why you think it is a R. Coccinea= this has yellowish/ creamish center
your picture and the IOSPE picture both have white center lip(you got the right name for your flower...do not doubt it