Every single invitation you receive in the Spond app will give you the option of turning off notifications for comments. There could be several reasons as to why you'd want to do this, such as too many comments or the specific content not being of interest to you.
You can turn off the notifications if you enter the event or group in the app. Choose the More tab to the top right corner, and then 'Stop push notifications”. You will no longer receive comments (alerts) from this particular event if you choose this option, but you can always change your mind later. This process is done in the same way.
Even if you turn off notifications for an event, you will still receive a push notification if the event is changed or cancelled by the administrator.