It's a vCoH replay right?
I don't like when people ignore the +10MU next to your base on Semois. It puts you at a disadvantage for no reason. Especially against Brits, you will want munis for flamers.
Pios don't beat brens

vs Emplacement spam is when you really need to just spam either pios or shrek grens. If you'd loaded 3 pios into your HT and gone around the back of that MG at the cutoff, you could've cut him off VERY easily.
You floated a fair amount of resources. Mines are devastating on Semois. Spam them. You needed a lot more grens and pios too. Paks aren't that great on Semois because there is a lot of shot blocking objects. Paks are also pretty bad against Stuarts and emplacements. Shreks are much more effective.
Going for an Ost was the right move but I noticed you were building a P4 at the end. You shouldn't have done this because you saw the Brit had built a Stag and was clearly going for FFs which dominate P4s. Better to build more Osts and have Paks/Shrek grens protect them.