Btw, I think thats the game with the Darkreapers losing badly against the PMs.
Anyway^^ Welcome to the Forum I am happy you found your way here.
I am really dissapointed in myself that I couldn't give your more tipps, but I almost never play Chaos.
I will try now anyway:
For the Buildorder: I always struggle more against double Heretics, they give you more mappresence, and you can upgrade one of them a bit later to grenadelaunchers for the Shurikenteam. If you leave them melee, that still gives you the option to flank with them.
You definitly need something to deal with the Shurikenteam. Raptors are also an option.
Havocs against WSE is always risky, he can just teleport onto them. I have seen people make them work, but... I don't really know how

Oh, and get an Aspiringchampion for your Heretics, I hate that guy.
For the Plaguechampion I would suggest Bilespewer or the Plaguesword. With the Bilespewer (as we saw in the game on the desertmap) you can get sneaky genbashes off. The Plaguesword is amazing against banshees. Both of these wargears can allow you to make better use of the Havoc if you get one, because when the Banshees can't make it into melee while the Havoc is occupied you just have to wait untill your Heretics/CSM force of the WSE.
In T2, I think plaguemarines were a good choice, because normally I would go for a fast Falcon at that point.
But when you had no power up at 4:50 and the grenade wiped the CSM it was basically game over.
For play by play, after watching the replay again, I would say: when the WSE decaped your VP engage him with one of the squads, and maybe use the other to go for my VP. When you had my VP at neutral and my WSE showed up, you can take the green cover and force him away. When you see a Shurikenplatform overextending, melee it with your CSM.
The Plaguechampion has good stayingpower behind cover. If you get anything behind greencover and worship it, I basically can't hurt it with rangedfire. The Plaguechampion himself in greencover is actually quite good against a setupteam, because his shooting doesn't get affected negatively.
I know this probably doesn't help much. Sorry!
I also think a big part might just be the basics and experience. If you want we can do some 1v1 where I play Techmarine or something. Then you can get more experience in.
As we talked about Automatch is sadly not very populated and customgames are the go to most of the time.
But good on you for keeping playing and wanting to improve! I wish I could help you more, but I am sure the people who know Chaos here will chime in also.