Font isue in Calc

When an .xlsx document is opened from Calc there comes an issue with the fonts. The font sizes in all cells of the original document are set to 10.5 but when opened in Libre Calc the fonts are set to different sizes 10.5 and 12 throughout all the cells. The font is a Unicode font called “Iskola potha”. I want to bring all the text to 10.5 font.

The problem is that it is not possible to change the font size by selecting all the cells and changing the font size through the formatting toolbar. How can I change the font size at once. And how can I minimize the formatting errors when transferring from xlsx to ods files?

If a file opens differently than how it was created in the authoring application (or, more precisely, differently than it renders in a reference application, such as MS Excel in case of XLSX), provided that there’s no missing dependencies on the system, like fonts, it is a bug. Please file it to the bug tracker, and attach a sample and screenshots.