the Online Help Article in German for how to make your spreadsheets accessible has some images/screenshots included, which have texts in them. There are several errors there for texts which have been added as a layer and some errors in the screenshots themselves, as they don't reflect a German installation of Excel. The article is marked up as machine translated. All in all, it's ok. However it lacks some times on fixed terms, such as menu entries or task pane titles.
1. Section Hinzufügen von Alternativtext zu Bildern in the Online Article
This section has two screenshots. The first one does not correspond to an actual installation of Excel 2016 in German. A correct one is the following screenshot.
The second screenshot from the online help article in this section looks like the following picture.
A correct one of the task pane is the following one:
The text, which has been added to the textbox is not correct too. I suggest to use: Die neuesten Modelle unserer Brailletastatur.
In the context text of this section, alternativ Text should be replaced by Alternativtext too, as that's the context menu entry name and title of the task pane.
2. Section Hinzufügen von Alternativtext zu Shapes und SmartArt-Grafiken in the Online Article
Like in the section mentionned above, there is a screenshot of the context menu in this section, which is incorrect. Currently, it looks in Excel like the following screenshot.
The second screenshot in this section also shows an in correct task pane for Excel in German (like above). I suggest to replace the screenshot (see above) and change the text from Unsere Stand der Messe to Unser Messestand.
3. Section Hinzufügen von Alternativtext zu PivotCharts in the Online Article
Like the previous 2 sections, the context menu screenshot include errors. A correct one is this one:
Same problem for the screenshot of the task pane too. I addiotionally suggest to change the added text to Diese Grafik zeigt die Zu- und Abnahme der Erträge über einen Zeitraum von fünf Jahren.
4. Section Dekoratives gestalten von visuellen Elementen in the Online Article
This section include a screenshot of the taskpane, which is incorrect. In the current version of Excel 2016 and having the checkbox checked, it looks like:
5. The other sections, starting with Hinzufügen von Alternativtext zu Bildern
In my current Excel version (1809 Build 10827.20084, Monthly Targeted), the format task pane does not include an option to add Alt-Text from the format task pane (removed). However, in older versions it was there and therefore maybe still the case for such versions. But I think, at sometime in the future, the info in the section will be outdated.