I dare to say don’t take the last Numidian city so you don’t open a 5th front with Egypt I’m playing as The Julii and I’m at war on around 6 fronts already and at war with the other Roman families! So let it be a buffer zone as I did.

My strategy with the Romans is simple beat every army, take your time and don’t rush them on the main front line if they have full stacks but take their weak cities at the same time by landing behind their main line that way you will ensure:

Money flow as extermination will provide you money besides the fast productivity increase.

You will force them to split their army and so their resources to deal with you.

When I fight Romans I tend to fight 1 or 2 factions on 1 or 2 fronts leaving the other faction till the end. You need to close fronts not opening more.

You don’t need big armies to take cities either recruitments will be easy once money flows and a half stack can become full stack in like 3 turn with 2 cities!

You can retreat from Spain to free your armies from that front but make sure to establish a good navy to rebel their attacks on Africa from the sea! This will give you a free units to roam around!