'Those products are not on sale' was rejected. = I think it happened because I used 'on sale' could it be ambiguous in Portuguese too?
Maybe that happened because 'on sale' agrees with a discount, so we say em/na promoção
Not necessarily. Esse/essa/isso can be used as a proximal (with aqui) which would mean it is translated with ‘this’ rather than ‘that’. Remember in Portuguese este/esta/isto corresponds to aqui, esse/essa/isso to aí (or as mentioned sometimes aqui, too) and aquele/aquela/aquilo to ali/lá.