One thing I am missing has to do with the Types one can find in the Metadata.

Some types are (Rust?!) base types such as ‘u32’, ‘bool’ or base structures such as ‘vec’. It is quite clear how to deal with these in an objective manner.

What I am missing has to do with the higher level objects such as T::Balance, ValidatorPrefs, Address, et cetera. The metadata is not self-descriptive enough to ‘know’ the composition of these higher level objects/structures. Hence an outside system (such as a 'generalized substrate explorer' [https://polkascan.io]) would need to ‘hard code’ the composition of such types or structures.

So I suppose what i am suggesting is to extend the metadata with a description of the composition of higher level objects and structures.

PS: discussion with Gavin on Riot hinted that this is non-trivial change and will likely not be picked up before 2020. Hence this issue is for future reference.