I found no way to make a tik send NatEvent field id 230 (https://www.iana.org/assignments/ipfix/ipfix.xhtml), and only do so upon creation/removal of a translation.
Is there a chance this can somehow be done?

I'll take it as a NO unfortunately, this makes mikrotik not suitable for small NATed isps in ex-ussr that need interoperability with lawful interception