Is it considered mockery of Allah to change the word "yu'akhkhiruhum" (He delays them) to "mu'akhkhiratuhum" (their rear/backside) in the verse: "He only delays them for a specified term," and then laugh about it?

The Quran must be glorified and protected. Not every laugh at a mistake in understanding or reciting a verse is considered mockery or disbelief, as long as it is not intentional. Mockery is defined as ridicule and belittlement. Not every laugh when sacred religious matters are mentioned is considered an act of disbelief.