Yes you are right and there is need for expansion to accept and includes some other currencies especially that of yours and ours, looking at the population IDR, NGN, PH, I think this people gambles more in the forum and if adding their currency would boost the growth of Rainbet.com then it would be a great idea for them to do so.
And not just only on the forum, but both outside that those countries you just mentioned are known to have a large market for gambling, but in and outside entirely, most especially my country Nigeria (i.e NGN), known to having the most population and a large number of gambling community. But however, I'm pretty much sure that Rainbet support team listen to suggestions, and I'm sure they will look forward to implementing this feature too with time.