Notes. Upper part: high-fidelity (F ≥ 0.9) candidate list extracted via blind search using LINESEEKER. Lower part: source candidates extracted by cross-matching ALMA CO(4–3) line-emitting candidates with F > 0.2 with the MUSE catalog of z ≥ 2.5 sources. ⁽¹⁾Identifier of ALMA CO(4–3) line-emitting (1.2 mm continuum-selected) candidates. The QSO and the nearby companion (Object B) are labeled as in Table 2. Object B has been selected by LINESEEKER together with the QSO as a single source. Here we report, separately the coordinate of the continuum peak of the QSO CTS G18.01 and Object B obtained via a visual inspection. Their S/N and the fidelity are set to the values provided by the code that are referred to the CO(4–3) peak of the QSO. ⁽²⁾Right ascension (ICRS). ⁽³⁾Declination (ICRS). ⁽⁴⁾Our best estimate of the CO(4–3) flux derived from the Gaussian fit of the line emission (see Sect. 3.6). ⁽⁵⁾Full width at half maximum of the CO line. ^(6), (7)CO(4–3) luminosities estimated via Eqs. (2) and (3), respectively. ⁽⁸⁾Maximum value of the S/N obtained through the different convolution (see Sect. 3). ⁽⁹⁾Fidelity and its uncertainties estimated by LINESEEKER using negative detections. ⁽¹⁰⁾Redshift estimate from the CO line centroid. ⁽¹¹⁾Velocity shift with respect to the QSO CTS G18.01 redshift. ⁽¹²⁾High-confidence redshift estimate from MUSE spectroscopic data. For those sources for which the redshift is not provided they either have an uncertain redshift measurement or they do not have any FUV-continuum counterpart from MUSE.