Yes, Fill the Floor and Interval Training rely on variable spawn interval. If ClamLix gets a D Lix release, Interval Training should be cut, and Fill the Floor should get adapted or cut.
Korean Border Crossing relied on the exact looks of Matt's bridge tile. There is no easy way to replicate that in Lix ≥ 0.7. But other missing levels are easier to replicate: I've attached an archive with screenshots of the Oriental levels in their original terrain. One of those screenshots is attached for example.
In June 2017, I autoconverted other levels from Matt's Oriental to my Oriental, I'll look into how I did that. The autoconversion preserved the rough shape, but not the exact terrain physics.
Levels with time limits can become trivial and need a deeper fix: Kill lixes that turn around, merge another group after delay into the first, ... If there is no fix, it's okay to ditch a level.
Shopping Cart race builder: In 0.6 and earlier, the builder generated her brick further behind by 2 hi-res pixels = 1 lo-res pixel. After a climber had hoisted, you could assign builder in 0.6 to have this backstep block the wall for subsequent climbers. The bridge was shorter to the front in 0.6.
I believe bumping head is the same in 0.6 and 0.9, but I cannot guarantee this.
Do you have a hunch about Shopping Cart Race's intended solution? Feel free to fix the level for this.
Forestidia, by now, you've become more knowledgeable than anyone about ClamLix. Would you like to become maintainer for this level set?
You would decide which levels to keep, change, or possibly cut altogether. I would include the pack in the main download once we have 100 % replay coverage and you're happy with the solutions. I won't know the solution to every level, I or others would occasionally ask you whether their solution is a backroute. Sometimes, ideally only once or twice per year, Lix physics change, requiring to re-cover some levels with proof replays.
It's your choice. It's okay to pass on the maintainership later, geoo started the lemforum pack in 2011 and passed maintainershop to Proxima early 2017. Clam merely left before we recognized the value of 100 % replay coverage and chosen maintainers.
-- Simon