If that's the type of translation/validation you are on a very slippery area as cultural background of the translator comes into the equation as does the need to form poetic/sound patterns within the result to match the music - its both contextual translation and lyric alignment.
Online translators vary in their capacity to provide contextual translation separate from literal translation and from your post you are looking for full contextual not literal. Contextual translation is very translator specific and that comes down to their personal language history.
For me I cover English, Spanish and Japanese languages spoken and English and Spanish written for translation and I have been watching Google translate over the years and for English/Spanish its actually pretty good at giving contextual translations that align with actual spoken Spanish or English (depending on the direction I am checking) ... but here is the issue, MY Spanish form is South American Spanish and Google is a modern Spanish Spanish form ... my 'native' or contextual translation into Spanish comes out sounding the equivalent English from 200yrs ago to a modern Spanish speaker from Spain while Google puts the sentences into modern Spanish.
On that basis I use google translate for German/English translation and English/French because my German and French are not adequate and the results still come out in fair English and people I am corresponding to in German and French are able to understand ... and most of that is on technical issues.
BUT none of that covers the additional need to not only do contextual translation but to then ensure it fits lyrically to the music ... you might end up with a movement of the wording for lyic purposes that makes for an 'odd' form when translated.