I don't know if my memory is playing tricks on me but I think there's a competition in Europe for juniors that includes figure skating. I think Plushenko participated in that event back in 96 or 97. Delobel & Schoenfelder also participated in that event while still juniors.
There is the bi-annual European Youth Olympic Festival, which basically fills this niche,
As you can see, lots of promising euro juniors, some with eventual sucessful senior careers are Past Medallists:
Men:
1993 Markus Leminen Thierry Cerez Evgeni Martynov
1995 Szabolcs Vidrai Vitali Danilchenko David Jaeschke
1997 Evgeni Plushenko Vakhtang Murvanidze Alexander Smokvin
1999 Stanislav Timchenko Stéphane Lambiel Kristoffer Berntsson
2003 Sergei Dobrin Yannick Ponsero Radomir Soumar
2005 Adrian Schultheiss Kim Lucine Nikita Mikhailov
2007 Artem Grigoryev Alexander Majorov Alexandre Briancon
2009 Viktor Romanenkov Stanislav Pertsov Gordei Gorshkov
2011 Petr Coufal Maksim Kovtun Simon Hocquaux
Ladies:
1993 Irina Slutskaya Elena Liashenko Vanessa Gusmeroli
1995 Nadezhda Kanaeva Vanessa Gusmeroli Krisztina Czakó
1997 Julia Soldatova Julia Lautowa Gwenaëlle Jullien
1999 Tamara Dorofejev Sarah Meier Svetlana Chernysheva
2003 Katharina Häcker Lina Johansson Viktória Pavuk
2005 Angelina Turenko Nicole Della Monica Kateryna Proyda
2007 Sonia Lafuente Margarita Tertychnaya Marcella De Trovato
2009 Miriam Ziegler Joshi Helgesson Anne Line Gjersem
2011 Polina Agafonova Ira vannut Monika Simancikova
It should be noted that except for the JGP and JW, no ISU ranking points are awarded for junior competitions.
Looking at the 54 medalists from the European Youth Olympics, only 5 went on to win World medals as seniors: Plushenko, Lambiel, Slutskaya, Gusmeroli, Soldatova. That's less than 10% of the medalists.
Given the ISU's current emphasis on "cream of the crop" selectivity for the GP and now ISU Championships (the new minimums), it seems unlikely that the ISU would be at all receptive to staging new competitions for a group of skaters with such limited potential. I'm surprised that the ISU hasn't cut the JGP to only 6 events.