I have been searching for a while and have not found any official statement about the call recording issue in Android (i.e. that it is not possible to reliably record calls on all phones). It may have the same lawsuit-fright induced reasons as a limitation of call recording in Google Voice (short notice here), but as mentioned, I could not find anything official.
Is there really nothing all over the Internet? And whom can I ask for more information? Google?
There is no call recording issue in Android. As you've seen, not all phones support it. Android supports call recording just fine, but this can only work if (1) the phone hardware can be told to send the call audio to the application processor of the phone (the main processor that apps run on), and (2) the baseband firmware (part of the phone's drivers) also supports this.
Some phones don't even have the hardware set up correctly for this, so there's no way call recording can ever work on these phones. Others have the right hardware, but no driver support. These phones could possibly work, but the SoC manufacturer would need to provide an update to the drivers, and the phone manufacturer (the OEM) would need to package this into a new ROM.
The bug report you linked to is completely pointless, which is why there's no comment from Google on it. Android already has a working API for call recording: it's now up to the remaining SoC and phone manufacturers to make it work on their phones.
