[Phanx]

This isn't a bug. LibSharedMedia assumes by default that fonts registered to it only support the Latin alphabet, and ignores them in Russian, Korean, or Chinese clients. If a font does include Cyrillic (Russian), Chinese, and/or Korean glyphs, the addon registering it needs to tell LSM that by passing the optional third argument to :Register.

See the API documentation here:

https://www.wowace.com/addons/libsha...-data-langmask

https://www.wowace.com/addons/libsha...mask-constants

Example of registering a font that includes Latin and Cyrillic glyphs:

local LSM = LibStub("LibSharedMedia-3.0")
LSM:Register("font", "PT Sans",
    "Interface\\AddOns\\PhanxMedia\\font\\PTSans.ttf",
    bit.bor(LSM.LOCALE_BIT_western, LSM.LOCALE_BIT_ruRU))

Example of registering a font with Latin and Chinese glyphs:

local LSM = LibStub("LibSharedMedia-3.0")
LSM:Register("font", "XYZ",
    "Interface\\AddOns\\PhanxMedia\\font\\XYZ.ttf",
    bit.bor(LSM.LOCALE_BIT_western, LSM.LOCALE_BIT_zhCN, LSM.LOCALE_BIT_zhTW))

Example of registering a font with Chinese and Korean glyphs (no Latin):

local LSM = LibStub("LibSharedMedia-3.0")
LSM:Register("font", "ABC",
    "Interface\\AddOns\\PhanxMedia\\font\\ABC.ttf",
    bit.bor(LSM.LOCALE_BIT_koKR, LSM.LOCALE_BIT_zhCN, LSM.LOCALE_BIT_zhTW))