its defiantly not a jewel cichlid i have 2 of them it the tank with them and i looked at some photos of keyhole cichlid and they as you said they dont have the line down there head and there body shape is a bit different
ill just add it has a really distinct yellow border around its fins
This is a gold or white saum. Most LFS are selling these as GT's The True GT has silverish white spots where the saum has brownish spots on each scale.