"experts from the US, Britain, Israel, Turkey" You have got to be having a laugh!
The Russians say that it was a terrorist ammo dump that was hit. It is of course equally possible that the terrorists did it to get the response it got. There are lots of past accusations regarding Assad just as there were lots of accusations about Saddam Hussein and Col. Qaddafi. It does not mean that the evidence is even remotely plausible but you can guarantee that those you listed will recite it even long after it is totally discredited. There is plenty of evidence of the US fabricating such evidence so the evidence is discredited by its own logic. Here we have evidence which is as believable as the nurse saying that Iraqi soldiers took babies out of their incubators and Iraq had WMDs i.e. not believable.