That is what the document says, but it does not detail in how it is actually done. If I transfer 100 USD, then it should somehow fluctuate to market conditions. So, the question is does GNU taler also vary the kudos to match FOrex rates? If not then how is currency exchange happening in this system.

No as someone stated its a gift card. A voucher that your bank is giving someone N dollars or whatever. So if the value of dollar decreases the value of your gift card is also decreasing but it is still the same amount of dollars but with less purchasing power

Edit: its an anonymous check

There is no currency exchange in this system. You just setup the system for each existing currency separately. The kudos is really just for development and demonstrating the system.

No, Kudos is not a real currency. It was an example for the explanation. Basically it seems the goal here is a sender-agnostic (or currency-agnostic I cant really tell which comes first) payment system which is pretty awesome

That's my understanding of it. Kudos is like a gift card.