Reading the game and adapt

So in a game, you carry out a plan, see some reactions from the opponent but what next when you start to see the trend of a spamming ? For example, I open with 3 MAA as Bulgarian, and then plan to add a stable to produce scouts. But then I see the walled up opponent have 4 MAA and archers showed up. At the moment do you discard your scout plan and immediately add an archery range ? In one recent game against the Celts I thought just a few skirms and a watch tower should do the job while I go up. But the opponent unexpectedly keep spamming MAA and archers for an extended fuedal and my small army composition couldn’t hold up. Eventually I went up and use a couple knights. But what I didn’t realize is the opponent keep spamming long sword and crossbow to my base. I am not sure how many barracks and ranges they have there but from the continuous unit spamming it seems at least 2 or 3 for each. So when you started to notice early signs of this, what would you do? Do you add more ranges and productions to counter them and match their numbers? If you do how do you adjust your econ? Forget about more TCs? Or do you start to mine more stones ASAP to beef up your defense and add TCs? Each option will have their own risks.