As far as I know, the cell formatting limits you to +-90 degrees. So not totally inverted.
You CAN invert a text box. You can have the text in the text box be from a cell.
The text box can be positioned over a cell and the properties should be "Move and size with cells".
Then, if you make the "Line Color" to be "No line" it will appear as a cell.... sort of.
I looked into browser encoding and neither MS Edge nor Google Chrome will let you force the encoding to UTF-8 or some other encoding that allows Unicode. I can only get the page to display correctly in Firefox, and I have to manually set it.
And, among other features these forums don't specify UTF-8 as the encoding. Drat!