In case an event is removed, calling the FMOD commandlet results in a crash, with this callstack:
UnrealEditor-SlateCore.dll!FSlateInvalidationRoot::FSlateInvalidationRoot() [REDACTED\Engine\Source\Runtime\SlateCore\Private\FastUpdate\SlateInvalidationRoot.cpp:215]
UnrealEditor-SlateCore.dll!SWindow::SWindow() [REDACTED\Engine\Source\Runtime\SlateCore\Private\Widgets\SWindow.cpp:2032]
UnrealEditor-UnrealEd.dll!SharedPointerInternals::NewIntrusiveReferenceController<1,SWindow>() [REDACTED\Engine\Source\Runtime\Core\Public\Templates\SharedPointerInternals.h:413]
UnrealEditor-UnrealEd.dll!ObjectTools::DeleteObjects() [REDACTED\Engine\Source\Editor\UnrealEd\Private\ObjectTools.cpp:2605]
UnrealEditor-FMODStudioEditor.dll!FFMODAssetBuilder::ProcessBanks() [REDACTED\Engine\Plugins\NSMExt\FMODStudio\Source\FMODStudioEditor\Private\FMODAssetBuilder.cpp:53]
UnrealEditor-FMODStudioEditor.dll!UFMODGenerateAssetsCommandlet::Main() [REDACTED\Engine\Plugins\NSMExt\FMODStudio\Source\FMODStudioEditor\Private\FMODGenerateAssetsCommandlet.cpp:65]
UnrealEditor-Cmd.exe!FEngineLoop::PreInitPostStartupScreen() [REDACTED\Engine\Source\Runtime\Launch\Private\LaunchEngineLoop.cpp:3659]
UnrealEditor-Cmd.exe!GuardedMain() [REDACTED\Engine\Source\Runtime\Launch\Private\Launch.cpp:137]
UnrealEditor-Cmd.exe!GuardedMainWrapper() [REDACTED\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:147]
UnrealEditor-Cmd.exe!LaunchWindowsStartup() [REDACTED\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:283]
UnrealEditor-Cmd.exe!WinMain() [REDACTED\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:330]
According to my analysis, the commandlet is trying to show a modal dialog to get confirmation about the deletion of assets. Unfortunately, Slate is not initialized while running commandlets.
A quick fix would be to pass !IsRunningCommandlet() as the second argument of the call to ObjectTools::DeleteObjects in FMODAssetBuilder.cpp, line 646, so that the confirmation is requested only when the commandlet is not being run.