  Most studies of Higgs sector CP violation focus on the detection of
CP-violating neutral Higgs-fermion Yukawa couplings, which yield P-odd,
CP-violating phenomena. There is some literature on purely bosonic signatures
of Higgs sector CP violation, where the simultaneous observation of three
processes (suitably chosen) constitutes a signal of P-even CP violation.
However, in the examples previously analyzed, some of the processes are
strongly suppressed in the approximate Higgs alignment limit (corresponding to
the existence of a Standard Model like Higgs boson as suggested by LHC data),
in which case the proposed CP-violating signals are difficult to observe in
practice. In this paper, we extend the existing literature by examining
processes that do not vanish in the Higgs alignment limit and whose
simultaneous observation would provide unambiguous evidence for scalar-mediated
P-even CP violation. We assess the discovery potential of such signals at
various future multi-TeV lepton (and $\gamma\gamma$) colliders. The potential
for detecting loop-induced P-even, CP-violating phenomena is also considered.
