Negative values for the ET, both potential and actual, usually refer to condensation.
See also "ERA5 mean evaporation rates data - Why is that negative?"
Regarding the ability of the physically-based hydrological models to handle condensation, I'd say that it's difficult to give you a general answer: it will depend on the specific math behind the ...
When push comes to shove, the highest evaporation rate per unut area corresponds to the highest average temperature.
As this pair of illustrations from NASA shows, that would be the Indian Ocean.
Simply put, the Indian Ocean misses both polar regions and hits the tropical and subtropical latitudes squarely, so it is warmer overall. Ergo more evaporation.