Can't statically link Boost Locale about locale HOT 1 OPEN

As the errors are all of "undefined reference to " you need to link to the ICU target. In particular icudata, icui18n, icuuc, e.g. by using find_package(ICU ...) and the targets ICU:data ICU::i18n ICU::uc

This is done automatically for shared libraries in general. Boost 1.75 config files add those dependencies too in all cases. So upgrading to Boost 1.75 or newer will also solve this.

Side note:

find_package(Boost COMPONENTS locale REQUIRED)

# This is redundant due to the above REQUIRED 
if(NOT Boost_FOUND)
    message(FATAL_ERROR "Some Boost libraries missing in the system")
endif()

from locale.