or was and will the update only be for houdini 17 ?

most of my team is on 17, but i'm on 16.5. they upgraded to ue 4.21 so i'm kinda trapped out atm with some work.

Hi,

Unfortunately, not officially, since we're not adding new features to 16.5, the last plugins versions on it will remain 4.19/4.20.
Your only solution would be to build the plugin yourself from the sources available on github.

You could either take an early H17/UE4.21 plugin and try to build it with 16.5, or build the current H16.5/UE4.20 plugin with 4.21.

You're likely going to have to change a few version numbers here and there and fix some compile errors due to missing/changed functions.