When Passolo (2016 or 2018) updates a string list where a parser comment for an existing, validated string is added/modified, the string will keep its status "Validated". But an added/modified parser comment may give the translator information that they did not have when they translated the original string, so it would make sense to set the string with the added/modified comment back to status "For Review" (blue), or at least have an option in the Passolo settings to enable/disable this string status change, in case it is not wanted/needed by all your Passolo customers.