For selecting 2 facets, the excepted request parameters are 1 parameter for each facets with the values separated by coma, such as :

user.input.facet.ContentReturnable$ProgramSearchable$indexingField$org.ametys.plugins.odf.Content.program$domain: content://47bb25ce-234c-4ed4-9e29-ce2c0227ddbe,content://fb0f2f0e-fc29-4ceb-8d2b-70bf1ef3b729

See FormSearchUserInputs#_retrieveUserFacets

It would simplify integration if multiple parameter with same name was supported :

user.input.facet.ContentReturnable$ProgramSearchable$indexingField$org.ametys.plugins.odf.Content.program$domain: content://47bb25ce-234c-4ed4-9e29-ce2c0227ddbe
user.input.facet.ContentReturnable$ProgramSearchable$indexingField$org.ametys.plugins.odf.Content.program$domain: content://fb0f2f0e-fc29-4ceb-8d2b-70bf1ef3b729

Currently to call search service for home page of ODF skin, we need to do some overkill javascript to change an hidden input with facet's name each time the real facet input is checked/unchecked

This is the same for sorts and maybe others.