Z270 K6 BIOS Setting for Watercooler

The one thing that I can see that is diminishing your AiO cooling performance is not the orientation of the fans but rather the fans themselves. They are the correct type (high static pressure) but they are aftermarket and tuned for silent operation. This means that even at full speed they are not pushing enough air. 

You could pick up something like these:

https://www.newegg.com/Product/Product.aspx?Item=N82E16835181027&cm_re=SP120-_-35-181-027-_-Product       (copy paste link)

Corsair's High Static Pressure fans always have an "SP" prefix then the fan size. The ones I linked are beastly and will make a lot of noise but they also push almost double the air of your current Enermax Twister Pressure fans.

Your temps are not great with the current setup but they are not terrible either. Whoever built the system for you was clearly going for a silence>performance setup. This isn't a bad thing, a lot of people prefer silence to cooling performance (so long as everything is within tolerance). If you want to tinker and improve things as well as possibly overclock in the future then I would pick up the fans I linked and have them installed for you. It would probably be best to have the person who built the setup do it for you, they know the build and if you have a warranty it saves you headaches later on. You could also ask them if they have the stock fans for the AiO, the ones on there did no come with the AiO cooler, it could save you some pennies if they can just slap the originals back on there for you.