🚀 go-pugleaf

I tried your situation here on my PC.  I have had similar problems with
a printer that was supposed to be emulating a HP Laserjet II and I 
was using a IIp driver.  It was ok in Windows but I couldn't get Excel
4.0 to print the true type fonts in different point sizes.  When I 
selected Laserjet II it corrected it.  But..... I know,you said it is
not the fault of the printer driver.  Here's a few other ideas,

Use Courier New, any point size.  It is not "proportional font", so all
text will line up where you expect them to.  Other fonts space the text
differently (i.e. iii takes up less space than ZZZ).

Remember you can change the column width from within Print Preview.  Hit 
the margin button, and then drag the little black buttons at the top
of the preview screen.  This is if you dont mind if the column widths
are changed.
If you want the col. widths to stay as they were, but you want the Format,
Border, Outline to block your single cell of text (that is overflowing
into the next column) do this: 
      Put the pointer into the cell (A1 for example)
      move the pointer to the lower left of the cell where it changes
      into a black cross
      Click and drag over into the second cell (A2)
      The text AND the border will move into cell A2
      Now delete the text in A2 with a DELETE and a Carriage Return
      Your text will now have the proper border around it.

Good luck

Rick