I edited in scare quotes for "complete" to make that clearer, but I mean in terms of at least having matching blocks/mobs despite many differing details.

A lot of the parity issues are due to Bedrock not reimplementing bugs from Java (quasi-connectivity aka "droppers are doors".)

There are issues other than not ported bugs. Redstone in bedrock is know to be unreliable.

For example, in Java version if you take a circuit and activate it with a button/lever - it would always behave in the same way. In bedrock same setup could have random result. And "random" is something you don't want in a large sophisticated contraption.

I'd guess it's caused by some race-conditions in bedrock implementation, but alas it wasn't fixed in 7 years.