Yep, that's about it! They're just for looks.
Besides A/C efficiency... Ah = Ah! 🤣
He already converted the 100 Ah 48v battery to be equivalent to 400 Ah on a 12V system. 600+ Ah on 12V is 200+ Ah better. One problem that can occur in a 48V RV system, is when the 48/12 DC-DC converter fails, you cannot use your trailer jacks, any cabin lighting, the CO detector, USB chargers, the fail-safe for the trailer brakes and every other 12VDC device (unless they also integrate a 12V battery).