I agree, the wording ("will now appear in a treasure chest") is confusing. What they mean is "will now appear in a treasure chest allotted to each party [if they drop]" rather than "will appear in a treasure chest allotted to the entire raid [if they drop]". But none of the raids were changed to 100% drop rate for every one of those items. Perhaps the 2B coffer in Copied Factory, but you will not see all of the orchestrion rolls, minions, etc. in every run on these raids.