The SQL that you can use to filter posts and find only the ones that have NOT been translated is this:

SELECT *
FROM wp_icl_translations
WHERE trid IN (SELECT trid
FROM wp_icl_translations GROUP BY trid having count(trid) = 1)

If you want to filter by a specific post type, like for “Pages” for example, you can use it like this:

SELECT *
FROM wp_icl_translations
WHERE trid IN (SELECT trid
FROM wp_icl_translations GROUP BY trid having count(trid) = 1) and element_type LIKE 'post_page'

If you want to filter by posts that HAVE an existing translation (as long as the site has 2 languages, not more), this might also work:

SELECT *
FROM wp_icl_translations
WHERE trid IN (SELECT trid
FROM wp_icl_translations GROUP BY trid having count(trid) = 2)