Point-contact (PC) spectroscopy measurements on antiferromagnetic (AF) $({T}_{N}\ensuremath{\simeq}5.2\phantom{\rule{0.3em}{0ex}}\mathrm{K})$ $\mathrm{Ho}{\mathrm{Ni}}_{2}{\mathrm{B}}_{2}\mathrm{C}$ single crystals in the normal and two different superconducting (SC) states (${T}_{c}\ensuremath{\simeq}8.5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and ${T}_{c}^{*}\ensuremath{\simeq}5.6\phantom{\rule{0.3em}{0ex}}\mathrm{K}$) are reported. The PC study of the electron-boson (phonon) interaction [EB(P)I] spectral function reveals pronounced phonon maxima at 16, 22, and $34\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$. The high-energy maxima at about 50 and $100\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ are resolved. Additionally, an admixture of a crystalline-electric-field (CEF) excitations with a maximum near $10\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ and a ``magnetic'' peak near $3\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ are observed. The contribution of the $10\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ peak in PC EPI constant ${\ensuremath{\lambda}}_{\mathrm{PC}}$ is evaluated as 20%--30%, while contribution of the high-energy modes at 50 and $100\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ amounts to about 10% for each maxima, so the superconductivity might be affected by CEF excitations. The SC gap in $\mathrm{Ho}{\mathrm{Ni}}_{2}{\mathrm{B}}_{2}\mathrm{C}$ exhibits a standard single-band BCS-type dependence but vanishes at ${T}_{c}^{*}\ensuremath{\simeq}5.6\phantom{\rule{0.3em}{0ex}}\mathrm{K}l{T}_{c}$, with $2\ensuremath{\Delta}∕{k}_{B}{T}_{c}^{*}\ensuremath{\simeq}3.9$. The strong coupling Eliashberg analysis of the low-temperature SC phase with ${T}_{c}^{*}\ensuremath{\simeq}5.6\phantom{\rule{0.3em}{0ex}}\mathrm{K}\ensuremath{\sim}{T}_{N}$, coexisting with the commensurate AF structure, suggests a sizable value of the EPI constant ${\ensuremath{\lambda}}_{s}\ensuremath{\sim}0.93$. We also provide strong support for our recently proposed ``Fermi surface (FS) separation'' scenario for the coexistence of magnetism and superconductivity in magnetic borocarbides, namely, that the superconductivity in the commensurate AF phase survives at a special (nearly isotropic) FS sheet without an admixture of $\mathrm{Ho}\phantom{\rule{0.2em}{0ex}}5d$ states. Above ${T}_{c}^{*}$, the SC features in the PC characteristics are strongly suppressed pointing to a specific weakened SC state between ${T}_{c}^{*}$ and ${T}_{c}$.