We don’t have a firm date unfortunately. As Eventing is considered a developer feature, it is a candidate for inclusion to CE, but I don’t know the scope or timing of it, sorry.
Regarding consistency - eventing sees mutations after they have occurred. So there is a time lag between mutation and handler running.
Regarding counters - you shouldn’t count mutations because mutations are de-duplicated. When you create a handler, it sees all documents (“everything”) and if a document was overwritten multiple times, it will only see the newest few versions of the given document will be seen by the handler. So you can’t rely on counting mutations even regardless of node failure.
Regarding Node failure - eventing engine checkpoints the sequence number up to which it has processed regularly. If there is a node failure, a new node takes over from the last checkpoint. This means that there can be duplicate processing within the checkpoint window but not missed processing. The checkpoint window size is configurable as an advanced setting.
We do have features to address some of above to make Eventing more comparable with View capability over time, but as those are not on a scheduled release yet, I won’t go into the details.
It seems to me that if @AnkitPrabhu can refine his suggestion, Views may work better for your use case.