"Mirrors"

My first attempt to mirror it ended in failure. Not every map can be translated into a playable mirror image without destroying its structure. Diamond was suitable for this; I think Spider can be realistically reworked. But more linear maps are difficult to balance. And they will have a problem with starting as Blue.

The problem wasn't linearity. It simply wasn't possible to create zones on the mirror map with sizes and contents similar to Jebus, and with satisfactory repeatability of these parameters. That is, it didn't even come to testing how the linearity of the map affects the playability of the mirror. Although the latest version of the mirrored Jebus for Warlords is much more playable than the first.

The mirrored Jebus will only be good with horizontal mirroring, but how to implement this...

I would like to hear at least some arguments in support of such a bold statement.
In fact, the method of mirroring has little effect. The resulting map structure is important. Theoretically, it is possible to create a structure on a regular two-plane mirror that completely repeats horizontal mirroring: place many lifts along one edge of the map. Only such a map will not be good.
On the mirror map, it is necessary to move away from using lifts so that you cannot collect the same closely located objects from one point. Therefore, cross-links between planes are used.

And creating horizontal symmetry is not so difficult technically, only there is not much point in it.