As discussed here: Sonoff Zigbee USB Dongle not working with IKEA Tradfri buttons, lots of people are have trouble with Ikea shortcut buttons (in particular — but possibly other Ikea remotes as well). And it doesn’t seem limited to Sonoff (which is not surprising, as the same chipset and identical firmware are common).
In that thread, there are reports of better success with zigbee2mqtt. I’m generally happy with ZHA, though, and the whole overhead of setting up mosquito and then zigbee2mqtt + HA integration seems like a lot. Meanwhile, the Ikea hub is just $30.
Is it still the case that the HA tradfri integration doesn’t get the button events? If that’s been solved, adding the Ikea hub and that integration just for the buttons seems sensible to me.
I moved from ZHA to Zigbee2Mqtt for my 15-device zigbee network and everything seems to be much more stable. Very glad I made the move. I don’t think it will be as much effort as you are thinking to get it set up. Can’t comment on the Ikea Tradfri buttons though as I don’t have any.