The logging version of FMOD is the main way to get more information about what’s going wrong. As for things to try, FMOD will make a choice between using PulseAudio or ALSA as the audio interface based on the response from pulseaudio --check. If PulseAudio is available it will use it otherwise it will fallback to using ALSA.
You can influence this choice (as a user) if PulseAudio is misbehaving. Use of the environment variable FMOD_ALSA_DEVICE allows you to specify an ALSA device to use instead of the default. Setting FMOD_ALSA_DEVICE = default should force the game to use the ALSA default device or any valid ALSA device name if that’s your preference.