To be honest I think this - and the "enharmonic changes" are probably more due to the Music Publishing software than the composer.I had issues with the split euph parts where an accidental was indicated on the upper line but not the lower but a few bars lower was indicated on both lines not clear, was it just poor proof reading and printing?
Also - if an accidental is stated in a bar, it carries on for the rest of that bar, unless its cancelled out. The Euph part is actually a single part, although it often (including this case) divides in 2 - the original rule still applies however which is why it appears how it does. Similar situation in Ex Terra.
Older "traditional" publishing often restated the accidental if it started in one line and fed to the other, but strictly speaking its grammatically incorrect musically I'd suggest. Of course, if you are publishing the Euph part as part 1 and part 2 thats different (you wouldnt expect a Euph to follow a Baritone accidental without stating it). Similar situations have existed on Solo Cornet parts for years.
I ALWAYS mark every affected note anyway on a contest piece - regardless of how well its written and whether the accidental is restated or not. I'd rather not get caught out on stage