It appears as if the value at address 0x00FFF42A changes upon triggering the appearance of Le Roof; specifically, it changes from 0x00 to 0x9F at frame 268651 of the 2013 TAS, upon the initial load of the text-box to get the Algo-Ring (but before it has any text), and then it changes back to 0x00 at frame 268697, upon the initial load of the text-box to use the Escapipe.
This value does not change in the WIP, despite opening the chest, although you do still get the Algo-Ring; I might bother to figure out how many frames to wait or what buttons on Controller 2 to press (I see that you press Z a great deal), but I'm still not entirely sure about whether this is the right path of inquiry.
I got this address by checking for every address that does not change right before opening that final ring-chest, and then checking for every address that changes between that point and the appearance of Le Roof, and only that address was found.
All testing was done in Gens-rr 11b, in which both the 2013 TAS and the WIP sync, even though all of the published TASes have used Gens-rr 11a.
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I don't know where you've already asked for help (I'm not regularly in the IRC channel, so I don't have logs of that), but you may consider asking the Phantasy Star RTA Discord (linked from
its speedrun.com page) or
the TASVideos Discord, if you haven't asked them lately; the RTA Discord may be relevant, because I have seen that same softlock happen in RTA runs.