Do we know of any workarounds in order to get good data?
Yes, like I showed above, editor.docLineFromVisible(editor.getFirstVisibleLine()), gives the actual document line number as derived from the display line number. Hence, the correct 75 that got printed on the second line in the final example box.
Addenda:
As implied in the editor section of the PythonScript docs when searching for “display line”, the visible line’s number is influenced by hidden lines and line wrapping. The “document line” is the real underlying line number for the line in the file. So there are a few conversion helpers: visibleFromDocLine converts the “document line” into the “display line”; docLineFromVisible converts the “display line” into “document line”; and wrapCount gives the number of “display lines” necessary to render the given “document line”. (All the other mentions of “display line” have to do with where HOME and END and their related commands end up.)
Similarly, if you want to set the first visible line (to scroll) based on an actual document line number, it would be editor.setFirstVisibleLine(editor.visibleFromDocLine(actualLineNumber))