Many thanks to peterlondon posting on the UK Flyer Forum for successfully "field testing" the iNavCalc-generated ".fpl" formatted files on the Garmin 695. This complements my own testing on my Garmin 795 device.
[If anyone is able to test on the Garmin 796 or 1000 series, please share your experience. I'm confident -- though not certain -- that those should work, too. But successful "field tests" by someone with access to those devices would prove it once and for all...]