In the € zone I usually get about 1000 point/€ spent (tax incl) given that VAT might be anywhere between 15-24% this is more or less correct.
I had only two FX related issues - one in Poland, where an email fixed the points, the other in Romania, where the "fix" was to convert local currency at the rate of 1:1, so I received fivefold the points. Wish it had been in Viet Nam