1. The { action, action_subtype, action_source, action_context } 4-tuple that we've implemented (based on @nshahquinn-wmf's suggested in T343331#9137988) covers all of the events that R&DS have listed in the spreadsheet
2. Establishing common verbs (e.g. init, click), is a valuable step but having concrete schemas for those verbs isn't
   1. Implementing convenience methods for the verbs is cheap
   2. It's not clear how to encourage R&DS/feature teams to review event types with these verbs in mind. For example: @jwang highlighted that a large swath of analytics/mediawiki/ipinfo_interaction event types could be mapped to click events, e.g. action=accept_disclaimer -> action=click,action_subtype=accept,action_source=disclaimer and action=close_disclaimer -> action=click,action_subtype=close,action_source=disclaimer
   3. Having concrete schemas for all of the proposed verbs is possible but inherently limits the types of events that can flow on a stream. Fortunately, we've implemented the new API in such a way that it uses the base schema by default (see #1) but can use an alternative schema if necessary. We should consider creating concrete schemas per verb when the need arises
3. The following actions don't have proposed verbs yet (but could still be captured – see #1):

@MNeisler, @cchen, and @KCVelaga all highlighted the need for the following verbs: edit, search, and error. Search could be also represented by represented by click or touch but I don't think edit and error could be represented by other verbs. Indeed, edit would be a suitable replacement for the firstChange action in the analytics/legacy/editattemptstep schema.