Wish I found this thread sooner. The function I made (that took me way too long) is below:
function CheckLetters($field){
$letters = [
0 => "a à á â ä æ ã å a",
1 => "c ç c c",
2 => "e é è ê ë e e e",
3 => "i i i í ì ï î",
4 => "l l",
5 => "n ñ n",
6 => "o o ø œ õ ó ò ö ô",
7 => "s ß s š",
8 => "u u ú ù ü û",
9 => "w w",
10 => "y y ÿ",
11 => "z z ž z",
];
foreach ($letters as &$values){
$newValue = substr($values, 0, 1);
$values = substr($values, 2, strlen($values));
$values = explode(" ", $values);
foreach ($values as &$oldValue){
while (strpos($field,$oldValue) !== false){
$field = preg_replace("/" . $oldValue . '/', $newValue, $field, 1);
}
}
}
return $field;
}