I'd guess (and most of what we do is guess about the future here) is that while the successful test is a big win for Coates, Cummins needs products that show that they can operate as their products do for much longer than a test period.
That seems to make sense and that's OK. Coates gets to second base and Cummins is waiting for them to cross the plate.
We want gratification as quickly as we can get it but Cummins isn't going to risk their butt on test data alone.
It's a big step forward, but this has a while to play out. Sure is better than, "Well we tried but it didn't work" ! A positive step is a positive step.