The Ts are for cleaning only, nothing else, an elbow would work if the holes were on the back of the tank.
When a BA secondary goes in and out of full siphon it is loud as heck and signals trouble.
What you have going there is a bit of an anomaly, it's pretty rare to set an open pipe to drain at a rate constant enough to keep an overflow box at a consistent level. If it ain't broken, don't fix it. With three stand pipes it has the same safety factor as a Bean Animal. The only thing you could gain with some elbows is maybe a minimal noise difference when the secondary gets used.
What do the other ends of those stand pipes drain in to? Under water in your sump? Above the water in your sump? In to socks?
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