I don't know if you can customize a monitored node to only send specific alerts, but you could increase the threshold for alerts you see very often so that they are only generated if they are above what you consider to be 'normal'.

Monitored nodes will send all the ALERTs/Exceptions to the AES (monitoring) node, hence in case you want only few ALERTs to be sent (see this: https://pdn.pega.com/sites/pdn.pega.com/files/help_v717/procomhelpmain.htm#concepts/concepts2/conceptsalerts.htm%3FTocPa…), you can assess increasing the threshold depending on your business requirements.