Substructure search with RDKit
I'm not sure about why it's not matching but when I carry out substructure matches in rdkit I use SMARTS instead https://www.daylight.com/dayhtml/doc/theory/theory.smarts.html

Here is what I would have done.

from rdkit import Chem

smiles_list = ['C12=CC=CC=C1C3=CC=CC4=C3C2=CC=C4', 'C12=CC=CC=C1C3=CC=C4C5=C(C=CC2=C35)C6=C4C=CC=C6', 'C12=CC=CC=C1C3=CC=C4C5=C(C=CC2=C35)C=C4', 'C12=CC=CC=C1C3=CC=C4C5=C(C=CC2=C35)C6=C4C=C7CCCCC7=C6', 'C12=CC=CC=C1C3=CC=C4C5=C(C=CC2=C35)C6=C4C=C7CC8=CC=CC=C8CC7=C6', 'c1ccccc1']

pattern = Chem.MolFromSmarts('[#6]12~[#6][#6]~[#6][#6]~[#6]1[#6]3~[#6][#6]~[#6][#6]4~[#6]3[#6]2~[#6][#6]~[#6]4')
for idx,smiles in enumerate(smiles_list):
    m = Chem.MolFromSmiles(smiles)
    print("Structure {}: pattern found {}".format(idx+1,m.HasSubstructMatch(pattern)))


and the output

Structure 1: pattern found True
Structure 2: pattern found True
Structure 3: pattern found True
Structure 4: pattern found True
Structure 5: pattern found True
Structure 6: pattern found False


I've added a Benzene smiles to show that it's not just matching everything. The SMARTS pattern I made probably could be better I think. I hope this helps anyway.