Hi,
how did you get a 16tq? With 20MHz protocol clock and desired 500kbps you will need either 8, 10 or 20 tq and also 40tq if CBT register is used. The setting of 80% sample point is possible.
You can try to test below tool for CAN bit calculation.
https://community.nxp.com/docs/DOC-342618
BR, Petr