Fix: revert st function change (#7387)

Update the 'st' function to use fallback message correctly.

## Summary

Will follow-up to figure out why some custom node descriptions trigger
an issue here.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7387-Fix-revert-st-function-change-2c66d73d3650816991a3ecc2a4740716)
by [Unito](https://www.unito.io)

src/i18n.ts

@@ -205,8 +205,8 @@ export const { t, te, d } = i18n.global
  *
  * @param key - The key to translate.
  * @param fallbackMessage - The fallback message to use if the key is not found.
- * @deprecated Remove, use the defaultMsg overload
  */
 export function st(key: string, fallbackMessage: string) {
-  return t(key, fallbackMessage)
+  // The normal defaultMsg overload fails in some cases for custom nodes
+  return te(key) ? t(key) : fallbackMessage
 }