This is probably way off-topic so I will make it quick as a teaching post...
For the full power of eac3to you may want to Google the Doom9 eac3to thread and see all the other commands. You can do all this completely within eac3to but trust me, it is a lot faster to use the other apps as you are only looking for subs and if you use eac3to for more than it will get more complicated and takes a lot longer. I can do a single disc is a matter of 45-seconds...tsMuxer is the longest part at about 30-secs.
You shouldn't need anything for eac3to to run since you are just using it to index the disc (folder). You can use it from ISO but it has to be mounted (if using W10 then a double click on the ISO should auto mounted it into explorer).
If you disc folder is on the e: drive and the folder name is "ThisMovieTitle" then your command will be as simple as
(eac3to does not need capitals if it has them)
with that command you should get:
1) 00001.mpls, 00001.m2ts, 1:31:15
- Chapters, 12 chapters
- h264/AVC, 1080p24 /1.001 (16:9)
- TrueHD, English, multi-channel, 48kHz
That reveals the main playlist that all programs will use to play this move. You need to see the detailed track list for this playlist so the command is this:
eac3to e:\thismovietitle\bdmv\playlist\00001.mpls 1)
Which will return the detail list of tracks...
M2TS, 1 video track, 1 audio track, 1 subtitle track, 1:31:15, 24p /1.001
1: Chapters, 12 chapters
2: h264/AVC, 1080p24 /1.001 (16:9)
3: TrueHD/AC3, English, 5.1 channels, 48kHz
(embedded: AC3, 5.1 channels, 640kbps, 48kHz)
4: Subtitle (PGS), English
So now you know that there is a single ENG sub track that you can demux with tsMuxer and import into BDSup2Sub to check for both forced but also for scope subs, which can be moved.