As I know there is Nuvi 4592LM SG/MY version too( it has English interface) but from what I can read on Malfreemaps forum there are many problems with this version too.
Even it is android device, it does not come pre-install with Google Play Store.
The Download Center (via Wifi) is kind of buggy, it keep pop up the software update in notification bar even i have tried install numerous time.
You need to complete the software update before update map in Download center. So with the bug mentioned in, i never get to update latest map via wifi. But still can update via PC updater
I guess to delete Baidu and the Chinese search engine from the unit you must root it.
You can use India map unlocked by gimgunlock+mapsigpatch if I remember well a post of one user in this forum.
You find India city Navigator map in Maps Index/Maps section.