PIC24 Primary Oscillator XT_PLL frequency is off by 3 percent
You're using the LPRC to 'measure' your crystal?  Usually that's done the other way around.

Have a look at the datasheet for your PIC - section 32.2, table 32-21.
You'll find the LPRC accuracy spec is +-20%, meaning it could be anywhere between 25kHz and 37kHz depending on various factors (temperature, supply voltage, ...).

I think your baud-rate troubles are coming from somewhere else and not from your crystal.

Show us your UART initialisation code as this is most likely where the trouble is.