Currently there is no way you can determine easily from looking at the price
guide what currency conversion has been used to determine the move from USD to
any other currency. As this figure has to be held/determined (calculated) somewhere,
whether in BL or by xe.xom it is available to be displayed and updated as regularly
as the price guide.
If Bricklink displayed that figure it would be very helpful for everyone's
use whether buying or selling. This is especially relevant for the last 6 months
sales which is a floating figure and is not easily determined - (it can be done,
but is very long winded and takes a lot more time and effort to get right.
As for the changes this would require, they are absolutely minimal from a coding
point of view and it would help to solve the never ending threads about currency
conversion and the price guide.
It would also help with Brickstock, but I am sure that is of no concern to Bricklink.