Update! The full score of the
Symphony is available from Presto Music here:
https://www.prestomusic.com/sheet-music/products/8903635--boellmann-leon-symphonie-en-fa-majeur-op-24 which at £35 is a bargain, compared to the prices charged for some orchestral scores!
For the sake of completenes, I see they also have the full (study) score of the
Symphonic Variations here:
https://www.prestomusic.com/sheet-music/products/8784634--boellmann-leon-variations-symphoniques-pour-violoncelle-et-orchestre-op-23 a snip at only £26.
Both appear to be reprints of the original Hoeflich editions.