I'll answer your question regarding direct playback of SACD-ISO file with i5 here in the forum because I am not an expert on this issue so I want to seek second opinion from the forum on this subject.
There is nothing much we can do to manipulate the sequence of playback in an ISO file by a portable player like i5. When you playback an ISO file, i5 will see this as ONE file, and it just happened that the files contained a number of paragraph (i.e., tracks) in a specific order. If you want to exercise some kind of control in the playback sequence, the player must be able to see the content as MULTIPLE FILES, and that is against the fundamental concept of an ISO file.
If you playback an ISO file with a computer, that will depends on the related features of playback software. Give the significantly higher processing power and amber random memory, software like JRiver and Audirvana Plus can provide additional control on ISO file then the native sequential playback.
For the sake of long term music file management, may I suggest you break down the SACD-ISO file into DSF file and fill up the metadata during the breakdown process.
iso2dsd is probably the most commonly used software for this purpose, but there are other choices such as "SACD Extract" and "ScarletBook"
Click
here for user discussion of iso2dsd operation.
A final reminder: some SACD-ISO file will use Lossless DST compression to reduce the file size, while Cayin i5 supports DST encoded SACD-ISO and DSF, a lot of other DAP does not support that, so it might be advisable to select "Convert DST to DSD" option (or equivalent) during the breakdown process. this will make sure the DSF file become readable by more DAP in the market.