I just discovered that one cannot enter characters using dead keys in the address bar of Epiphany, which are crucial to some web addresses (such as articles in Wikipedias other than the English one).
For example, if I try to enter 'ó' by pressing first the ´ key and then the O key, all I get is 'o' instead of 'ó' - the dead key has no effect on the address bar.
Non-ASCII characters requiring no dead keys are entered fine: pressing Ñ or Ç in the Spanish keyboard enters the corresponding characters just fine.
Also, dead keys work fine in any other text areas of the document being displayed or the program itself - it's just the address bar that doesn't accept them.