Right now it's impossible to use the magic words and special page aliases in the Latin script on the Serbian Wikipedia.
For example, some of the localized magic words (according to MessagesSr_ec.php) for #REDIRECT are #ПРЕУСМЕРИ, #преусмери, #ПРЕУСМЈЕРИ, #преусмјери, and those work fine. However, their Latin counterparts found in MessagesSr_el.php (#PREUSMERI, #preusmeri, #PREUSMJERI, #preusmjeri) don't work at all. They should all be usable. The Latin magic words for image options are also treated as 'bogus-image-options'.
Also, many of these items are missing the Ijekavian variant that's a part of the Serbian standard. For example, 'img_left' should have лијево as an alias alongside the current ones, 'currentmonth' should have ТРЕНУТНИМЈЕСЕЦ, ТЕКУЋИМЈЕСЕЦ, ТРЕНУТНИ_МЈЕСЕЦ and ТЕКУЋИ_МЈЕСЕЦ, and so on.
Because there's this comment on line 160 of this file, I didn't want to provide all the additional aliases for Ijekavian right away, but instead wait for someone to let me know where all the values are stored if they're not taken from there.