1σ confidence contours for cosmological structure parameters Ω_m, σ₈, S₈, and the intrinsic alignment amplitude A₁, constrained by the γγ,  3 × 2 pt,  3^ph × 2 pt, and 6 × 2 pt forecast configurations with ‘incoherently’ (dashed contours and curves) and ‘coherently’ (solid contours and curves) biased redshift distributions, and no nuisance model (‘do nothing’) for redshift recalibration (see Table 2 for a summary of forecast configurations). Colours here denote probe configurations as in Fig. 12 (also given by the legend), whilst line styles denote the type of redshift bias (as described in Sect. 3.1.1). Dashed black cross-hairs display the fiducial, true parameter values. The legend gives for each contour set: the probe combination; the true redshift distribution (i.e. the type of redshift bias); the n(z) nuisance model (given as ‘×’ here, for the ‘do nothing’ model); the FoM on the S₈ − Ω_m plane (Sect. 4); and the parameter bias in the same plane (comparing posterior means to their equivalents for the $n_z^{\mathrm{true}}:\mathrm{do}\mathrm{nothing}$ cases, Sect. 4; Eq. (4.2)). Significant mis-estimations are seen in almost all cases, with variable errors according to the type of redshift bias.