[ISW- 5x4PT series] Could ISW-5xxPT series supports 4 PoE power class 3 devices (PoE power class 3 range is from 6.49 Watts to 12.95 Watts)?

Yes, ISW-5xxPT series could support 4 PoE power class 3 devices, because ISW-5xxPT series provides full PoE power up to 60 Watts maximum totally and could provides completely 15.4 Watts power on every single PoE port, also ISW-5xxPT series supports PoE power classifies detection and will reserve enough PoE power for your PoE device automatically.