The rules for recording large numbers are not much different from English. The main difference to English is that in German,
. are swapped. The comma is used as a decimal point, and the dot is used for grouping thousands (optionally, can be the empty string or a blank as well).
- German: 123.456.789
- alternatives: 123 456 789 (or just 123456789, if you want to annoy your readers)
- (English: 123,456,789)
- German: 3,1415926...
- (English: 3.1415926...)
- German: 123.456.792,1415926...
- (English: 123,456,792.1415926...)
Like Stephi said in a comment, the "569,0" could be an implicit abbreviation where a bank person is talking about Thousands or Millions of currency and just drops the tiresome zeros. I'd expect a small annotation somewhere which explains the abbreviation "scale", like "569,01 ... (footnote: 1: in Tausend Euro)".
The 34,8000 only makes sense in a context where a minimum decimal precision is mandatory. But I've never encountered that in hand-writing. This is something usually done in Excel sheets only.
So in summary, the numbers in your document either conform to some house rules (ie. a common notation used by the relevant industry), or they just lack some context, like the footnotes I mentioned, but they are not something I'd consider standard notation.