I have never seen the musicals, but it seems that it is the opposite:
it is the musicals that were influenced by the manga and the anime.
If the manga and Crystal vaguely imply that Pluto loves Endymion, the musicals explicitly confirm it.
La Soldier is one of my favorite songs and I don’t know who composed it, but they did a great job.
Wrong. Seramyu is a big part of the franchise and its influence on the anime and manga is undeniable.
-La Soldier appears in episode 88.
-The ending of the episode 88's battle is similar to the first musical. No wonder, because the first musical and that episode were written by Tomita.
-Kunihiko Ikuhara loved La Soldier so much that wanted something similar for the R Movie: the Moon Revenge theme.
-Moon Lips (the original cast of the musicals sang the second version of Moonlight Densetsu used in S, SuperS opening and episode 200 ending.
-Akiko Kosaka, a legend of Seramyu, was behind some songs of the 90's anime, R movie, Crystal, and the new films Eternal & Cosmos. Also her songs were a big influence in the music department of Sailor Moon.
-Naoko Takeuchi attended the first musical rehearsals and the song performed by Minako 'Love on a tree lined street' when she meets Saito (Kunzite), was the big influence for her to write Sailor V's chapter 8 which has the same title.
Source: Naoko's commentaries in the original tankoban of Sailor V volume 2. I can translate the comment if you want.
-The writter and producer of Sailor Moon S musical revisions, SuperS, Stars and Eien Densetsu musicals, also wrote and produced the first 5 musicals of Nelke, from La Reconquista to Le Mouvement Final.
-Fisheye redemption was written by this producer for the SuperS musical that was fleshed out later in the SuperS anime. Also, the Black Dream Hole concept for the SuperS movie came from this musical as well.
-PGSM existence is not only a Naoko's whim. The popularity of Seramyu was decisive.
-From 1995 onwards Seramyu surpassed the anime and manga's popularity. The Nelke musicals have been well-received by the public in comparison to Crystal/Eternal/Cosmos.
-Seramyu has developed some concepts the anime and the manga never did.