I am wondering KaleunMarco, if maybe dlsa isn't referring to the old
FOTRS = Fall of the Rising Sun, as opposed to the
FotRSU = Fall of the Rising Sun Ultimate? There is a world of difference in many aspects. Even though FotRSU is based on FOTRS (which grew from TMO v1.7), it includes parts of ~all~ versions of FOTRS, v1.2, v1.3 & v2.0 ship Rosters, etc., but has alterations to supporting files, such as the torpedo sim files, as well as additions to the mod from other sources.
Can you tell us dlsa which version of what you are naming as "FOTRS", it is that you have? Also, it can be very difficult at times, to "see" the torpedo tracks from the periscope, especially if the sea is up any.