Yea, it seems the long walk around is intended in the level, which is why the steel is there where the basher tunnel is in the middle (block a backroute according to Icho). Not to mention that as you have seen, the level was just a huge problem to edit in Superlemmini due to other unexpected problems, like a climber climbing out to the left at the bottom when it's not supposed to, climbing over a 1 pixel ceiling in the basher tunnel and so had to extend the terrain vertically, and adding more terrain so that a basher can bash the OWW because it can't bash very gentle slopes. Of course, in other custom packs designed for Superlemmini, these issues weren't present, and so I had no idea of knowing these would cause problems on plenty of Reunion levels that you converted. Good thing you're doing these conversion projects to Superlemmini so that some of the quirks of the engine can be discovered and be reported to Tsyu. Still hoping he comes on soon, but let's not get our hopes up for that. In the meantime, you just do whatever it takes to get the level working in the engine. Even Icho said in the OP of his conversion of Dovelems and Pimolems that he "tried to get as close to the original as possible, although some had to be changed in order to work with NL mechanics," such as the fake steel levels being completely reworked so that they have visible terrain mixed in with the steel, making them not blind and guess the path type of levels. Thus, if levels need to be changed in some way so that it's still possible in a particular engine, at the cost of looking nice or the elimination of central tricks intended for the level or anything really, so be it.
Glad to see you're rechecking the levels of your conversion projects, as it's possible that some things might have been overseen