[itsme]

So simple & efficient, just using features that are already there. Thanks samibe for sharing this tip.

Let me add another hint:
I often do not add a book completely but only select certain songs from the CSV import list. In that case it's easier to find the songs I want to import when the list is sorted alfabetically by title.
But it's really easy to change the sort order of the CSV file. Most of my CSV files contain an additional column with either the startpage in the PDF of every song or the printed page number. This is possible because MobileSheets just ignores columns where the header field is not a known MobileSheets database field name. So I just can open the CSV with LibreOffice (other spreadsheet programs like Excel should also work) and change the sort order between sort by title for selecting single songs during CSV import and sort by page number for importing the whole book according to samibe's advice.