yup, silver archer is a problem because you have bashira and victoria, which is why I said " Victoria can temporarily replace the need to get a Spica, but you will likely lack silver archers to CC her, so just use bashira + Soma/Daniela for now"
your next step should be leveling the cc'd units and lilia to 30 and getting iris and adele to cc30. remember to get some affection, and if you feel it's worth it, you can buy goddess blessings to try for more stars around 3 days before event ends