I understand your frustration, but unfortunately we only can make each Forest update compatible with one Arnold version.
When we compile a new version of the plugin, we use the latest Arnold SDK available, so the plugin is compatible with it.
To make things worse, there are different numerations between the Arnold version (currently 7.1), which the MaxToA package which includes it (currently 126.96.36.199).
As general rule, we suggest to use the latest Forest update from our website, and the latest MaxToA package available for your 3DS Max version, which are available here
Futhermore, Autodesk doesn't provide MaxToA updates to all Max versions (for example Max 2020 is not included in latest udpates). In this case, you can search the latest MaxToA for your Max version in the archive
I can confirm the latest MaxToA available for Max 2020 (MaxToA 188.8.131.52) works fine with our latest Forest version (7.4.3).
If you have not access to the latest Forest update, you should try with an older MaxToA package.