This has been a very interesting conversation for me NoImNotNineVolt and I get a sense you are honestly trying to understand the issues rather than to simply propagandize for a terrorist organization that has purposefully placed its own civilian population in harm's way to gain international sympathy when that population is harmed. However you appear to be bending far over backwards to avoid confronting full recognition of the Hamas strategy and the complicity of UNRWA.
The UNRWA spokesperson you quote, Chris Gunness, is according to what I have read from him over the years either aligned with Hamas or as the saying goes, a "useful idiot" for them.
Let's look at Mr. Gunness' prevarications.
"'According to longstanding UN practice in UN humanitarian operations worldwide, incidents involving unexploded ordnance that could endanger beneficiaries and staff are referred to the local authorities,' Gunness told The Daily Beast in a statement. 'Local authorities fall under the government of national consensus in Ramallah. They pledged to pass a message to all parties not to violate UNRWA neutrality.'
"'As far as we are concerned, the government that we are dealing with now is the government of national consensus and they have authority over the organization that we dealt with for getting rid of these rockets from our school,' he said. 'We handed them over to the relevant authorities, and that organization, as it were, the experts that came and did it, are under the government of national consensus in Ramallah.'"
The "government of national consensus in Ramallah"; Mr. Gunness likes that phrase so much he repeats it over and over. This is the Fatah organization whose members have been tortured and murdered by Hamas. So UNRWA handed the rockets over to "local authorities", i.e., Hamas, but not to worry - those local authorities report to the folks they murder whenever possible.
The Daily Beast article you quote from states: "UNRWA has opened an investigation into the rockets found in its school in July but may not release all of its findings. 'When our report comes out, we will take a decision on what we will release,' Gunness said." Thus, UNRWA is "investigating", will write a "report" on their findings, but "may not release all of" the findings. I call "bullshit" on Mr. Gunness.
That same article goes on to state: "UNRWA had other options, though. The agency isn't in the ordnance disposal business, of course. But it could have turned the rockets over to a third party. It could have closed off the school until another international organization with ordnance disposal skills secured the area." and "The fate of the rockets is now unknown."
Quoting that Daily Beast article again: "In a statement on July 17, UNRWA condemned the storing of rockets in the school and called the incident the 'first of its kind' in the Gaza Strip. In November 2012, UNRWA denied claims by the IDF that Hamas was using UNRWA facilities to store and fire rockets." Then of course there was the second "discovery" of its kind a few days later, and then the third a couple of days ago. Do you think that perhaps Mr. Gunness is beginning to see a pattern emerging? Probably so, because despite that investigation that UNRWA will be making, they "may not release all of its findings". Of course they won't, they are protecting Hamas in the arena of world opinion, and they don't have much to work with besides cover-up.
Finally you write, unsurprisingly given your bend-over-backwards acceptance of the circumlocutions provided by bullshit artist Chris Gunness, "Probably the latter, but do you feel that this excuses Israel's war crimes? Do two wrongs now make a right?" I'll tell you my friend, that war is hell, and Hamas purposely makes it more hellish for the citizens of Gaza so that Hamas can reap the propaganda benefit of world outrage when photographs of dead and injured children appear in the news media. And I'll tell you further that the humanitarian restraint demonstrated by Israel time and time again heartens me that it is possible for humanity to stand on a higher moral ground even in the midst of bloody war against an enemy whose tactics are immoral, are in fact, evil.