I must admit I never tried to investigate the primary sources of Buddhism. Thanks for mentioning that. Today I’ve learned, Pali Canon is actually huge, it seems surely more than 40 books!
The Pāli Canon falls into three general categories, called (from Pali , meaning "basket", referring to the receptacles…en.wikipedia.org
And some of those that read the original languages claim that the English translation is “bad.”
So allow me to have my doubts that the 500-something pages of “one of the first German Buddhists” happens to be the best short version of the whole material. But I can surely understand it was inspiring for you, especially if it was the most accessible book for you. Maybe an English translation of it would really be something that would be interesting for a whole world.
To make the things more complicated, that’s still not the only canon of Buddhism, so even reading only that I would miss the differences that exist by all Buddhists that have other canons.