Problem:
Astra Custom Layout translation not showing.
Solution:
The custom layout was being inserted into the page using "astra_custom_layout" shortcode and this shortcode perhaps wasn't registered with WPML. This is common because plugins and themes keep evolving and introduce new features (widgets, shortcodes, blocks and etc).
However, it is important to note, that the custom layout itself was being translated, in ATE. So there was need for this shortcode to be recognized by WPML, so WPML could convert its IDs (i.e. use translated version ID on translation):