I know it's not that cut out bla bla, have to adapt etc. etc.
Btw, build order works. But COH2 it's more like in the most ideal situation that what and when i wanna build stuff kinda thing. You do have to adapt in the sense you need to play in a way that you can build in the order you were going without getting "Shanked".
Here are some BO's for OST(/ means they are both needed but their order is inter changeable):
1. MG->Gren->Gren->Gren->BF1/Healing Bunker(make it with first squad to retreat)->PG/AT gun and then it get's a little muddy but based on how you played you might need to build another at gun or MG. After this you wanna build a P4 after that your gonna have to go with flow really.
2. same as 1 but replace Grens with Ostruppen.
3. MG->AssGren->AssGren->MG the rest is the same as the others with the exception you need 1 more PG.
Now you have to remember 1 thing, BO's in this game works as weapons similar to other games it has strengths that allow you to pressure your opponent and weaknesses that your gonna have to deal with.
1 is Basic, requires average level OST skill(the avg skill for ost is much higher than other factions btw) to use it's weakness is that it slower and weaker in contrast to all allied starts save for SOV penal or sniper starts. And grens get bodied hard by all other infantry late game.
2 is a high skill ceiling BO, as Ostruppen are even worse than grens they won't beat anyone. The strength of this BO is that your start is fast you can cover a lot of ground and skip T1 building outright and have access to PG's and P4's much sooner.
3 is ummm.... a noob stomper, If your opponent don't know how to deal with that then you can have a field day otherwise it's kinda not that good. Pro's can make it work cause vehicle micro is something they have over normal players, so don't try this unless you have vehicle decent micro.