Here's a breakdown of the tenses and meanings:
* "poyittunḍayirikkum" - This implies someone was likely in the process of going somewhere at a certain point in the past.
* "cheythitunḍayirikkum" - This implies someone was likely in the process of doing something at a certain point in the past.
These phrases are often used to express speculation or inference about past events.
Here are some English translations that convey the same meaning:
* "He must have been going"
* "She must have been doing it"
* "They were probably on their way"
* "It's likely they were working on it"
The specific English translation you choose will depend on the context and the specific action being described.