Beissa, What exactly do you mean by "the Unicode method to enter special characters"? I know what Unicode is, but I don't know how that refers to a method of entering characters.
You are correct about the need to enter a space if the accented letter is at the end of the answer. I have been experimenting some more with Pelé, and have found that it is accepted correctly if I enter the last letter as an Alt+number combination, and then press the spacebar. It also works if I paste it from Microsoft Word, and if I enter it via the Windows Character Map tool. In those cases, the space isn't necessary.
But the above applies only to PCs running Windows. The only other platform I have access to is Android. I find I can successfully enter accented characters using the French keyboard on my Android tablet, without needing the additional space.
So, to summarise, it seems that an accented letter will be accepted, but if it comes at the end of the answer, and if you enter it via the Alt+number method, you will need to enter a space. In all other cases, the character should be accepted straight away.
That's good enough for me. In the majority of cases, my guess is that an English-speaking player (or, more precisely, one who uses an English keyboard) will enter the un-accented form of the letter. So, provided you set the quiz up to accept that as an alternative, there should be no problem.
Mike