Okay, finally got the original nrf24l01 SMD modules with the square chip visible... As exptected, things work just fine now, so the culprit of my issues was really the incompatible/fake "nrf24l01" SMD modules with the epoxy blob. If you want to use normal nrf24l01+ modules together with this smd gateway, DO
NOT USE the smd module with the epoxy blob, as they won't work.
Using only the fake SMD modules might work, too, but mixing the fake modules with real ones does not work.
Hi @acb and others, regarding "Do you know if there is a version of this board that is pad-compatible with the C-versions of these HopeRF RFM69s before I go searching? (Since I believe the C-versions are also pad-compatible with the RFM95s…)" - did you find any alternative?
I'm in the same boat looking for an adapter from NRF24 to the footprint of RFM69*C = RFM95/96.