I've found WRE is relatively easy, even in VH/VH.
So, here is a bunch of tweaks to make Romans life as hard as it is supposed to be.
- Battles - Recruitment Priority
German factions can recruit plenty of cheap light infantry units - without control, the AI makes full stacks of skirmishers that are systematically slaughtered by any modest Roman army.
I have introduced a recruitment offset in the EDU like this:
Siege weapons have offset 0
All other units start with offset 1
Cavalry units get a priority bonus of 2
Unit costing more than 300 get a priority bonus of 1
Unit costing more than 700 get a priority bonus of 1
Bonuses are cumulative: a cav unit costing 1000 gets 2 + 1 + 1
Restarted a WRE campaign and by turn #32 I've started seeing Vandal stacks populated with Gardingi inf, heavy spearment, Cnithe, etc - no easy life to Roman legions any more !
I have not tried yet, but these changes should have a limited impact on the Roman AI.
Note that in the EDU, I had already modified Roman recruitment costs like this:
Upkeep reduced by 25%
Recruitment = upkeep
Turns increased by 50% (eg comitatenses 4 turns, aux pal sr 6 turns, etc)
Plumbatae must be toned down - they can make a big difference. However, their number can't be lowered (they were obviously 5, as seen in the models). Range is already low (40m). So we are left with the attack factor: in the EDU, I have lowered it by some 20%, but it must probably be further reduced.
Alliances with Berbers/Suebi are too easy for the Romans - desr_strat modified: now best relationship to WRE is "poor".
Increased penalties for "distance to capital", "religious unrest", "no governance".
I want to see some riotings ! An empire with 44 regions must be a pain in the neck to manage.
Some effects are already visible after 20-30 turns. More info later. Your feedback appreciated.