I've just checked, and it appears that indeed Amasis is the default font for T3 ...
But this doesn't solve the issue why T1 can display diacritics in titles (which are printed with Swis) but not in the content (which is printed with Dutch) if left without any font definitions - and I was able to see those diacritics in the fonts, as anyone can see in the figures.
This bugs me up - although the workaround/s is/are simple (or about
).