Tl;DR
I played this matchup, did an early spear+ram push and was denied via archers. I then added MAA into the mix, and this extra beefiness was good enough to force the engagement with numbers on his side of the map. I had max efficiency prelates at all times (effectively outpacing the french in eco) and once it was safe swapped to fish/deer to get more units en masse. French still need nerfed even though I can potentially win the matchup without safe water.
As has been mentioned, I played a game against a french as HRE on mongolian heights. I got a fairly good number of sheep, around 20 (Mongolian Heights has a ton), and It went fairly standard, he went school+archery, royal knights + archers, I went pure barracks, up to 4 if I remember correctly. I tried an admittedly too early 16 spear push with a ram, using the ram to jump in and out with the spears to force aggression up close. I killed some vills and cav, but ultimately it got shut down. I had already gotten my +1 range defense.
After, I realized on 1 TC I had to keep aggression to force engagements to prevent him out eco-ing me. So I started building about 20 MAA and spears each, and building more rams.
Once I added MAA into the mix, I could rely on them enough to not take damage to the archers, and the spears en-masse were significant enough to win against the 10-12 knights he had.
On the topic of early economy in for HRE, I typically go P, V, V (up to 8 vills since you start with 6), Vx4-5, prelate, Vx3, repeat vx4-5, prelate, v3 over and over. Once my initial 3 sheep are done or I’m running low on stock, I will swap the 8+prelate onto gold while my scout collects or brings back more. This gives me a bank so I don’t idle for food, and gives me a fair amount of prelates to use for healing/gathering via the increased gold gen early on. Remember, prelates are super vills - When they don’t bug out, they give 40% of a vill, 8 times. That’s 3.2vills for the time it takes to get one, which is effectively a 20% production rate increase for the cost of 100 gold and needing 8 other vills with him to get him to work properly.
This is multiplicative for other food sources. If you have safe fish, you can send 8 vills+prelate to get 1.125 food per second compared to a french sheep farmer giving .625. That’s essentially double your opponent’s vills! Boars are similar (18%faster compared to sheep), and so in safe matchups (delhi, china) or 4v4 you can get a boar and do a similar shenanigan of fast food. You can then place prelates on mills to give a 40% perpetual food increase, as this works beautifully.
This all being said though, french needs nerfed.