It's already spelled in Irish!
Rego Sen's birth name is Regaip A. Sen.
Rimi Sen's birth name is Shubhomitra Sen.
Sushmita Sen's birth name is Sushmita Shubeer Sen.
Victor Sen Yung's birth name is Yung, Sen.
Sen (千) means thousand. You use sen to count such as; 'ni sen' (二千) which means 2,000 'go sen' (五千) is 5,000 etc.
Raima Sen's birth name is Raima Dev Varma.
No, it is not an Irish name.
The name is not a traditional Irish name and has no historical Irish spelling.
Sun-Yat-Sen was the name of a Chinese political leader. There will not be a definition for a name of a specific person.
Nandana Sen Aruna Shields Neeru Bajwa
No, Irish is not the name of a saint.
There is no Irish version of the name.