Venom tribute is funny - it's Abaddon's project, he plays on most of the tracks with one or two guys of the claimed bands. Except Voivod, which seems to have recorded the song without his help. However, I remember somebody saying (maybe here, maybe elsewhere - maybe it was Skulhed?) that there's only Snake and Piggy and a drum machine on this recording. Don't quote me on this one, I'm really not sure
The second track you mention I haven't heard anything about, thanks for sharing.
There was also a Die Kreuzen cover song Man In The Trees released on the Lean Into It tribute compilation.
I believe this was their last recording with Piggy alive, Jasonic lineup (not counting two posthumous albums).
The Nile Song single contains a rare live version of Tribal Convictions recorded live at The Roxy, West Hollywood, CA.
Fix My Heart and We Carry On singles contain radio edits of the title songs.
A radio edit of 21CSM appears on Japanese edition of Phobos.
There were also a couple of B-sides from Eric era released on Nanoman single and Negatron Japanese edition, eventually found their way to Kronik (if you can call these "non-album" tracks).
Casper, your friendly ghost