Ordinals after a period

Right now the automatic feature for ordn substitutes for ordinals only after figures:

sub [zero one two three four five six seven eight nine] [A a]' by ordfeminine;
sub [zero one two three four five six seven eight nine] [O o]' by ordmasculine;

What about cases like 1.a or 2.a ?

I can write the code myself but this seems to be a very common thing to have in ordn feature.
Are there any cases where this is not recommended?

True. The spec even mentions this case:

Example: The user applies this feature to turn 2.o into 2.ยบ (abbreviation for secundo).

BTW this is also a feature that may cause a semantic change.