It is demonstrated in the (pseudo)spin S = 1 formalism that the structure of antiphase domain boundaries in the phase of charge ordering of a mixed-valence system of the Cu^1+, 2+, 3+ “triplet” type in cuprates on a two-dimensional square lattice depends to a considerable extent on on-site correlation parameter U. The results of computer modeling on large square lattices illustrate the change in the boundary structure (from a homogeneous monovalent nonconducting structure of the Cu^2+ type to a filamentary superconducting one) induced by a relatively small variation of positive U values.