Present 16 - Nice one on saving so many more than required, but obviously a backroute - it shouldn't be possible to save more than 87.
Present 18 - Backroute, but I think you know that Any time you engage in pixel manipulation to pull off some seemingly impossible feat, you can be pretty sure it wasn't intended.
Present 20 - Exactly as intended!
Present 22 - Slight backroute due to the fact I didn't realize the far-right wall was already 6 pixels high and you could create a barrier with a single builder (which you could sacrifice since you didn't have to use the bomber). I'm happy to call it an alternative solution though as it's at least as good as the intended.
Present 24 - Acceptable solution More or less intended, just that I platform the second-highest little gap rather than the top one, but IIRC Guigui solved it the same way as you, so I guess that way of doing it must be more logical than mine.
Present 26 - Total backroute. Not a single element correct haha but well done for finding it through some insane shenanigans!
Present 28 - Another backroute - it's not supposed to be that straightforward!
Present 30 - Major backroute, with some elements correct (and very quickly deduced, well done!). The main backroute-y part is freeing the crowd with a basher from below. I thought I had already blocked this but apparently not!

Extra lemmings saved and builder remain that was just pretty awesome solution. Damn this level was mega cunning, its take a lot time to solved