I can somewhat understand the PDF issue as it has had issues in previous times displaying different currency symbols. This was due to the font type of the theme in particular, where the fix was to revert the font type back to Arial. UTF-8 is the character set that the PDF uses with all fonts (the default theme uses Arial and UTF-8). So I can only assume that it would have something to do with this. However what I don't understand is why the default wont handle it....
Now, your jpgs can't be found so I can't actually view these however I have run a few tests and have come up with different results.
First test was putting the accents into the description fields. The admin area was able to handle this with no problems. Viewing the PDF did work however replaced the accent character with a few strange symbols (Ã©).
Second test was to put the accents in the column names. I replaced 'e's in the description and price columns. This still displayed in the admin however broke the calculation functionality therefore not showing totals for that row and the entire invoice. Regarding the invoice, this again displayed the column names fine but also had the totals calculations missing. I am assuming that this is because PHP and JS can't read the accent characters and its causing an error.
Now these differences could be due to the way the character came about (I don't know how you had inserted the character, but I copy and pasted the accent character from your post above).
Let me do a bit of research into this for both the admin area and the PDF and I'll get back to you. Unfortunately I can't give you a time frame for when I will get back to you with any news as my schedule is rather full atm as well as me doing this in my spare time around full time work and life in general. If you discover anything that may help, please don't hesitate to add it to this thread.
Thanks - hope we can get this sorted for you soon.