Consider the popular Irish name Seán. It has become known around the world, and while some people write ‘Shaun’ or ‘Shawn’, most are familiar with ‘Sean’.
And if you’re speaking English only, then ‘Sean’ is fine.
Except in Irish, without the ‘á’, it’s pronounced ‘shan’ – and it has a different meaning.
sean (adj.) Old, aged; mature.
Add the ‘á’, and Sean becomes Seán, a proper noun, and a popular name.