Rod, most maps available are bad; such lakes are not named or even wrongly named. You are surely right in thinking that it is one of those.
And you are probably right guessing that your Parosphromenus spec. is one of those many slightly different variants of a bintan-type coming from Jambi/Sumatra.
The “Borneo Pisciculture”: I have just tried (14.08.2914) to scan the pictures at the site, but I did not see any species name (it was a facebook site; I could not find any free direct site). There are linkei and spec. Blue line and possibly others to be seen, but no fish that resembles the original P. gunawani that I had and have bred (Linke’s won picture ist to be seen at the species account in our website; it is a very good photo which shows the stoutness of the body and the colouring of edges of the unpaired fins quite nicely).
The photo is reproduced in the Finke/Hallmann 200-pages-book on Parosphromenus (“Prachtguramis”) containing many photos never shown before; some copies (not many) are still available.