How to Count Features in a Feature Type in FME?

Not tried this, but it sounds like you should be able to use the Counter transformer and specify your feature_type_name (or fme_feature_type if you haven't renamed it) attribute as the "Counter Name" parameter:

Counter Name

Create separate sequences of numbers to be assigned, either by placing several Counter transformers with each having a different counter name, or by choosing an attribute whose value will be used as the counter name as each feature passes through. (In effect, using an attribute to supply the Counter name is like having a Group By option for the Counter.)

I also found this discussion on FME Community Answers.

Try a group by in statistics calculator as fme_feature type, you need to expose the fme feature type from the reader.