That’s fascinating. It seems the original meaning was similar to chi, prana, or spirit. The meanderings of words are indeed unpredictable!
The root meaning of dukkha/sukha are said to be “hard to bear, easy to bear” or something like that. However I am not really convinced that we can go any further than the words themselves. Pleasure and pain are very basic concepts, and so far as I know, that’s what they mean all the way down. Having said which, I haven’t seen an analysis of how they’re used in the Vedic context.
I’ve never had a problem with using suffering for dukkha. It seems on the whole pretty accurate.