Is it permissible to pray behind an imam who makes mistakes in pronouncing some Arabic words when reciting the Qur’an?

If the Imam is unable to pronounce some words due to a foreign accent or a lisp, his imamate is valid for someone like him, and the prayer behind him is sufficient if there is no one who can pronounce properly. However, if there is someone who can pronounce all words correctly, then the imamate of an Imam who cannot pronounce properly is not valid.