It is in fact a bit confusing to fight macedonians in the north. IF they survive the greeks, they nearly always turn north fighting germans and sarmatians.
There are only a few conditions for the macedonian strategy:
Code:
hold_regions Macedonia Syria Nile_Delta Babylonia Attica Rhodos
in descr_win_conditions.txt and
Code:
core_attitudes macedon, 0 dacia
core_attitudes macedon, 0 britons
core_attitudes macedon, 600 seleucid
core_attitudes macedon, 600 greek_cities
core_attitudes macedon, 600 egypt
in descr_strat.txt.
Where 600 means war and 0 means Alliance.
IF the AI would strictly follow this conditions, the macedonians shouldn't turn north. But this is probably all that can be done by the modders to "guide" the AI's expansion. And I guess the thing when it comes to "artificial intelligence" is, that it must not follow the rules, but it could.
That's why it's called an intelligence...