I think some interpretation is needed when reading the key fob sheet. The TPMS sheet explicitly says 433 MHz, but unless the world is upside down I can promise you the key fob long-range function also operates on 433 MHz. If FCA (or any OEM) cranked up the power of the 125 kHz signal to transmit "long range" they'd be in violation of FCC... and also of the analogous regulatory bodies overseas. There is no leeway here. The allotted frequencies are written in stone.
The RFH uses low-frequency to communicate with key fob in-cab and near-cab but long range is different. One of the stated inputs of the RFH is "Remote start antenna's RF signal". So... even though not mentioned in great lengths, an RF antenna does exist, it's connected to the RFH, and it's used to capture commands from the key fob. Even though only remote start is mentioned, the same needs to be true for the other key fob commands: door lock, tailgate, E/E mode, panic, etc.
Antenna's are inherently two-way; if it can transmit, it can receive. What prevents two-way operation is the IC; the chip in the key fob. It takes money, space, and battery power to add the demodulation circuitry needed to capture an over-the-air signal and convert it to digital. There are no regulations preventing FCA from making it two-way but when dealing with compact battery powered devices, the usability and feature tradeoffs become a serious discussion within development groups.
Battery life is stated to be approximately 3 years. Making a two-way key fob could potentially reduce life to 2 years or less. I'd rather have the longer life. The key fob RF is one-way and the LED only blinks when the key fob is transmitting RF. There is also no stated RF output from the RFH. LF, on the other hand, is obviously two-way.