Struggling to understand a sentence in _The Moon and Sixpence_

Solution 1:

I don't think your break-down of the sentence is correct. I understand the sentence in the following way:

• When people who knew Strickland in the past realized he was a major artist, they gave interviews about him to journalists and articles bagan to appear in the press.

The sentence can be reduced to something like this:

• And when such as had come in contact with Strickland in the past (...) discovered (...) that (...) authentic genius had rubbed shoulders with them there began to appear in the magazines of France and America a succession of articles (...).

A comma between them and there would make the sentence clearer.

There is not the adverb you find in I'll see you there, pronounced /ðɛə/ but the existential there you find in there is, there are..., pronounced /ðə/. It's the formal grammatical subject of began:

• there began to appear (...) a succession of articles...

In other words:

• a succession of articles began to appear