How to reuse existig DataSet CSV Import function from custom module?

Shall I use Xibo API to send CSV file to Datasets or is there any way to reuse existing CSV Import function from my custom module for which I am building CSV parsing to get values inside Datasets to display it on Display Templates similarly used in weather module.

It is probably easiest to manipulate the DataSet object directly in your module. You could use the csv import code as inspiration but you should find the dataset object quite straight forward.

That being said, using the API would guarantee the interface didn’t change during an upgrade.