At least the S-series *DO* have the language strings in the firmware. I've seen and compared both S5IS and A720 firmwares, the A720 does not seem to have any language strings in them, which is also what you concluded. Still, on the S5IS, I have been unable to locate the functions / offsets responsible for properly showing the proper strings. I guess they're using some odd data structure to keep the pointers in, as they are not discovered by IDA. This means that even with the strings, the task will be pretty tough, and also because of this, I can't look up where the strings should be on the A-series.