"Undetected" in that part of the world doesn't necessarily mean the technology worked...
how could they tell it was effective in that part of the world, did they check the rubble and the dust for a color change? are the craters a different shape from the ones already there?
as for 'undetected', when the enemy's using 50's era HiMAD (but without the radars because those were already blown up in the fighting earlier this year) and shoulder-launched heat-seekrs that require eyes-on to engage (not really possible at 30K+ feet altitude) that's kind of a no-prize. You can do it in a Hawker Hunter under those conditions. Irregulars and the remnant of a conscript army working with handmedowns and scraps isn't a test of your 'stealth' features, it's fish in a barrel for anything with wings and working avionics.
Put it up against an airforce that isn't flying fifty year old planes armed with junkyard special munitions, who have a working early-warning net, and functional ADA network and aren't a mixture of untrained volunteers, political appointees, etc. etc. first, see how it does and maybe then, you've got something to announce when it works.
but the Middle East? Syria's a basket case. Unless those strikes were at Russian positions with established defenses and secure perimeters, it's not really a test of anything except map-reading for the pilot.
