Afaik, that tool is abandoned by @whatever127. But this is basically the same (the tool probably means "Cumulative Update" when it says only "Update"):
I downloaded the duump and the problem at the end - turns off - there is no end option - only the window disappears. At the end I couldn't print the scren because the window closes
If you created ISO with install.wim, that's correct. For smaller ISO, you need to create ISO with install.esd.
@zbigniew59 You might try this. move the install.wim to a new folder then run this script - it will compress your .wim to a much smaller .esd then you insert the .esd back and make you new .iso dism /export-image /SourceImageFile:E:\ent\install.wim /SourceIndex:1 /DestinationImageFile:E:\ent\install.esd /Compress:Recovery /CheckIntegrity
Does turning on cleaning and resetbase cause any errors or other negative effects? Or a problem with installing next updates?
Depends on the update to be installed next, some report no problems with public CU's but have problems with RP or SLOW ring CU's. At the moment there are no problems with KB4515384 (18362/3.356) and kb4508451 (18362.10019) after cleanups.
What’s with just not cleaning up the ISO, this has no negative points (only file size) and there will be no errors, right?
Depends on the size of your HDD & available space. If you have a 1 TB HDD shouldn't be a problem but many people need the approx. 15 GB that cleanup will give them.
Where is that based on? Cleanup will gain approx. 3GB on average, online, and approx 1000MB offline. Online cleanup will be ran periodically by windows.