Apparently quendite grass cannot be created from jungle grass blocks. Also, grass doesn't spread from jungle grass blocks to adjacent vanilla dirt blocks. This makes it very hard to create an elven portal in the Far Harad Jungle.
Maybe this is intentional, maybe this just hasn't been implemented yet or has been overlooked.
Either creation of quendite grass from jungle grass blocks or spread of grass from jungle grass blocks to vanilla dirt would be very desirable to implement.
Apart from the above, upon creation of an elven portal in the Far Harad Jungle, it is recommended to consider the appearance of crocodiles. They seem to spawn close to any body of water, whatever the size or altitude. Could placing a banner prevent this?