Created attachment 138682 [details]
style names in groupedbar (left) and in the Styles menu (right)
In groupedbars of Calc (View - Toolbar Layout - Notebookbar and View - Notebookbar - Groupedbar full/compact), there is the Styles group that includes styles corresponding with the Styles menu of menu bar - excepting the items "Header 1" and "Header 2" which should be named "Heading 1" and "Heading 2" as it is in the menu (see the screenshot).
I can confirm with Version: 18.104.22.168.alpha0+
Build ID: 88f6ffeb9e0c0b942c2b0bc9d60af7bb7a6caaf8
CPU threads: 4; OS: Linux 4.4; UI render: default; VCL: gtk3;
fixed in groupdebar_compact