I think crappy sound is expected with this bootleg series, more a love of the music than the SQ.
From Allmusic's Fred Thomas - "As with so many of the entries in Neil Young's Official Bootleg Series, Somewhere Under the Rainbow circulated as a rough audience recorded bootleg for decades before this official release, and professional mastering can only polish the raw sound quality to a certain point. For this kind of live document, the imperfections are part of the charm."
I'm not a big fan of "rough" bootlegs, but some finding it charming I guess.