I think MT4 allows 100 EAs in 100 different charts. The sottware doesn’t know what happens inside tha EA file (in terms of existing more than 1 strategy in each). I’ve already been using over 40 Portfolio EAs in one MT4, with around 10 strategies each (about 400 strategies).
What I’m actually afraid of is it’s capacity to deal with the amount of strategies (900~1000). I don’t think there’s a way to find out if orders are not being triggered.