What are the most popular technical models used for forecasting exchange rates in international economics?
Writing as an academic modeller who would use the outputs of such models, what's required (and what I look for as a reviewer) is:


reproducibility: the algorithm is described with sufficient detail to enable someone else to reimplement it;
validation, using data that is completely distinct from the calibration dataset; and
that the output is a distribution of forecasts, not just point values.


Such a distribution can then be fed into ensemble modelling. So instead of using a single forecast of the future value of a currency pair, I could feed in the distribution to a monte carlo simulator or similar.

It doesn't need to have the right expected value, nor a correct value for volatility (or any other moment).

All that makes it essentially useless for trading. And that's a good thing, because no one of sound mind would give away a profitable forex forecaster: such a forecaster would immediately render itself obsolete as it entered common use.