Thanks for the clarification. That solves the mystery. I see that Table 14 in the datasheet must be the table of allowable bandwidths that you're referring to.
I think I was thrown off by the RadioHead RF69 library, which gives "a selected subset of common modulation types" and which doesn't even mention the corresponding bandwidths:
FSK_Rb2Fd5 = 0, ///< FSK, Whitening, Rb = 2kbs, Fd = 5kHz
FSK_Rb2_4Fd4_8, ///< FSK, Whitening, Rb = 2.4kbs, Fd = 4.8kHz
FSK_Rb4_8Fd9_6, ///< FSK, Whitening, Rb = 4.8kbs, Fd = 9.6kHz
FSK_Rb9_6Fd19_2, ///< FSK, Whitening, Rb = 9.6kbs, Fd = 19.2kHz
FSK_Rb19_2Fd38_4, ///< FSK, Whitening, Rb = 19.2kbs, Fd = 38.4kHz
FSK_Rb38_4Fd76_8, ///< FSK, Whitening, Rb = 38.4kbs, Fd = 76.8kHz
FSK_Rb57_6Fd120, ///< FSK, Whitening, Rb = 57.6kbs, Fd = 120kHz
FSK_Rb125Fd125, ///< FSK, Whitening, Rb = 125kbs, Fd = 125kHz
FSK_Rb250Fd250, ///< FSK, Whitening, Rb = 250kbs, Fd = 250kHz
FSK_Rb55555Fd50, ///< FSK, Whitening, Rb = 55555kbs,Fd = 50kHz for RFM69 lib compatibility
Because of that, I had gathered the erroneous impression that bandwidth was a dependent value, derived from BitRate and FDEV.
Interestingly, the radiohead library states "If you need another configuration, use the register calculator. and call setModemRegisters() with your desired settings. " So, it would appear that there does exist some kind of calculator for the RFM69, perhaps a spreadsheet similar to the RF22B calculator:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjd1vGPlvzJAhXEbiYKHYyUAcwQFggcMAA&url=http%3A%2F%2Fwww.hoperf.com%2Fupload%2Frf%2FRF22B%252023B%252031B%252042B%252043B%2520Register%2520Settings_RevB1-v5.xls&usg=AFQjCNGlwgyomYH-WSWInI2winrQu1Oq6A&bvm=bv.110151844,d.eWEAnyone seen a register calculator for the RFM69?