The character limitation for some strings is defined as 240 characters however translators can enter more than 240 characters in the field and they are still able to complete the jobs.
The status still changes to Complete and the resulting file is finalized.
Today, the system does not prevent the translator to enter more characters than what's authorized.
The 240 number is picked up from the XML has an indicative piece of information.
However, the idea is to alert the translator about this limitation and that's the purpose of the QA check.
So, to sum it up:
first, translators would see the colored "size constraint" icon on the right hand side whenever there's is a maximum number of characters they should be aware of.
Secondly, as they type, they will see the instant word count on the top right corner. It turns red as soon as they exceed that number.
Making translators run the final QA check will be a third option to avoid the described issue.
If translators would be asked to run "Advanced QA check" before completing their job, they will be alerted and will be able to fix this, or add a comment if there's no way they can make the description shorter.