добавь cvar в interfaces
если не получится то вот
class ICvar : public IAppSystem
{
public:
    virtual CVarDLLIdentifier_t        AllocateDLLIdentifier() = 0; // 9
    virtual void                       RegisterConCommand(ConCommandBase *pCommandBase) = 0; //10
    virtual void                       UnregisterConCommand(ConCommandBase *pCommandBase) = 0;
    virtual void                       UnregisterConCommands(CVarDLLIdentifier_t id) = 0;
    virtual const char*                GetCommandLineValue(const char *pVariableName) = 0;
    virtual ConCommandBase*            FindCommandBase(const char *name) = 0;
    virtual const ConCommandBase*      FindCommandBase(const char *name) const = 0;
    virtual ConVar*                    FindVar(const char *var_name) = 0; //16
    virtual const ConVar*              FindVar(const char *var_name) const = 0;
    virtual ConCommand*                FindCommand(const char *name) = 0;
    virtual const ConCommand*          FindCommand(const char *name) const = 0;
    virtual void                       InstallGlobalChangeCallback(FnChangeCallback_t callback) = 0;
    virtual void                       RemoveGlobalChangeCallback(FnChangeCallback_t callback) = 0;
    virtual void                       CallGlobalChangeCallbacks(ConVar *var, const char *pOldString, float flOldValue) = 0;
    virtual void                       InstallConsoleDisplayFunc(IConsoleDisplayFunc* pDisplayFunc) = 0;
    virtual void                       RemoveConsoleDisplayFunc(IConsoleDisplayFunc* pDisplayFunc) = 0;
    virtual void                       ConsoleColorPrintf(const uint8_t* clr, const char *pFormat, ...) const = 0;
    virtual void                       ConsolePrintf(const char *pFormat, ...) const = 0;
    virtual void                       ConsoleDPrintf(const char *pFormat, ...) const = 0;
    virtual void                       RevertFlaggedConVars(int nFlag) = 0;
};
inline ICvar*                g_CVar           = nullptr;
надеюсь знаешь куда >>