For you and anyone else reading, you do not have to remove the injector rails to replace valve cover seals. The easiest way to change that cover is to jack that side of the engine up off the crossmember. This gives you room for the lower rear bolt removal and to lift the cover from the engine. You remove the engine mount nut from that side and raise the engine a few inches with a bottle jack or floor jack.
As for the injector seals, use WD-40 or a light coating of mineral oil on the seals before you insert the injectors into the rail and intake. Be sure the injectors seat all the way into the rails and intake before you tighten the bolts down. To test for leaks, turn the key on/off a couple times to reprime the rails with fuel and pressure. You'll more likely find a twisted seal at the leak site, or it may be cut. I hope you ordered the seals from Subaru or got Subaru seals. Aftermarket don't fit.
As for the injector seals, use WD-40 or a light coating of mineral oil on the seals before you insert the injectors into the rail and intake. Be sure the injectors seat all the way into the rails and intake before you tighten the bolts down. To test for leaks, turn the key on/off a couple times to reprime the rails with fuel and pressure. You'll more likely find a twisted seal at the leak site, or it may be cut. I hope you ordered the seals from Subaru or got Subaru seals. Aftermarket don't fit.