The issue is described here:

and it’s the way I assumed this plugin would work.

the first and second filter are based in a taxonomy child terms. 

we have here one taxonomy with two parent terms: Paisajes and Temas.

-term1 (first filter widget) = «Paisajes»
-term2 (first filter widget) = «Temas»

when a search is being done I want to be able to search by all the Paisajes and Temas child terms I choose from with and AND relation. not with an OR relation as it currently as unexpected works.

for example. if I select childterm1 and childterm 4 I should see all the posts which belong to the childterm1 AND to the childterm2. but currently the filter shows all the posts in the childterm1 OR the childterm2.

there’s another issue described here