The database lists "JTAG" but not what functions are available over this interface; eg, programming only? on-chip debug?...

I think there are also some chips with on-chip debug, but no JTAG.

There's an error in the Triscend TE5 and Zylogic ZE5 entries: it says no UART, but they all have one "hard" UART.

Devices like the *E5 are always problematic for such databases: it says no other IO busses, no PWM, 1 UART, etc - but you could actually implement all of these in the programmable logic!
Similarly, it says the devices have on-chip XRAM but no on-chip Code space. This is not true - they have on-chip RAM that can be used as XDATA and/or CODE as required!

I imagine the uPSDs would have similar issues...