Hi! Could you advise me on the correct flow here? I need to add a custom button on the Job record type via a user event script and send an email passing some data from the current record. Currently, I have created a user event script, added a button, and pointed to a client script where the action of the function is defined. However, when I try to import the 'N/render' module in my client script, the console shows an Uncaught Error: Load timeout for modules: N/render. Then I realized it's not available in the client script. How can I generate an email in this case?

fair chance you can just render the email in the user event

If it's just html code in the email. You could create the email body in the client script itself. If you do need to render though then call a suitelet.

I thought about rendering the email within user event script, but I dont know ow to detect if a custom button was clicked

you can make the button set a field on record that you get in the user event