Thanks for the replay, WillLem. Indeed, by taking the route you took, I would think an additional minute is needed in order to make the level passable. I wonder what was going through the author's mind when he made this level for Superlemmini. It would be nice to get a hold of him, but I don't think he's ever been on this forum. According to the levelpack info on the website I linked to, this level was chosen as one of the best by both the author and the Lemmings community. This would probably suggest that the level is passable in its current iteration, but if it is the only way I can think of is through the giant leap glitch. However, I have never ever gotten this particular glitch to work on any level. Perhaps someone else can get it to work? More importantly, does that glitch carry over from Dos and Lemmini to Superlemmini?
I just confirmed that the level is indeed possible with an additional minute, which means a time limit of 11 minutes instead of the current 10 minutes will make the level solvable the way it is. However, using WillLem's building up to the very top at the very end solution, only 2 seconds remained, so it really comes down to the wire, but it will be passable with 1 extra minute added while keeping the skillset the same. I think I ended up using all 50 builders, surprisingly, and so absolutely no wasting builders at all! So, maybe the author saved the time limit for the level wrong?