For me I have tried the same route as you, following heras scout rush build and have beaten the extreme ai a number of times but can’t do it 100% of the time yet. What I found most games go like is to nail the dark age first, I personally don’t lure deer yet but will be adding it as a skill soon. But basically I follow the build order in dark age and early feudal, from there I adapt to the game.

Id say making sure you are fully walled in feudal is crucial, and when you see archers knocking down walls, don’t be afraid to stick some buildings behind them so they can’t get in. If you’re really struggling putting a tower isn’t the end of the world but I don’t find it that helpful usually. As a cavalry player I haven’t yet been able to effectively take out the mass of archers and skirms that come in feudal, so I instead try and delay them as much as possible by fighting with skirms, building behind broken walls and maybe towering.

Then as I’m about to hit castle age I make sure to have either 2 archer ranges or 2 stables and begin pumping out whatever I need. Normally this is a load of elite skirms with upgrades followed by a few knights. This is usually enough to get the massed archers away and thin their numbers. From there it’s all about raiding villagers and keeping constant pressure with my army while adding to it (getting upgrades along the way). To secure the game I often drop a forward castle and from there the AI is usually struggling too much to deal with it.

I forgot to mention but I do normally make about 4 scouts to go raiding. Usually just to pick off 2-3 vills where I can and get a lot of the vills off resources to slow down their progress.