[Ekaterina]

Ah...not quite. You're doing a couple of things here that may cause things to act in a way you don't expect them to.

local addon, ns = ...
local name, ns = ...
local cfg = CreateFrame('Frame')
local _, class = UnitClass('player')
local cfg = {}

What you are doing here is creating two variables (addon and name) that hold the same information (the Addon Name). Then with cfg, first you are creating it as a frame, then re-defining it as a table.

Try this.
Config file:

local addonName, ns = ...
local _, class = UnitClass('player')
local mediaPath = "Interface\\AddOns\\oUF_Kygo\\Media\\"
 
local cfg = {
   texture = mediaPath.."normTex2.tga",
   bgFile = mediaPath.."backdrop",
   edgeFile = mediaPath.."backdrop_edge",
   Icon = mediaPath.."Neal_border",
   CPoint = mediaPath.."NCPoint",
   font = "Interface\\AddOns\\oUF_Kygo\\Media\\Fonts\\ExpresswayRg.ttf", 
   fontsize = 10,
   fontflag = "OUTLINE, MONOCHROME", -- Font flags should be in capitals and separated by a comma
 
   ClassPowerText = {
        Priest = {26/255, 160/255, 255/255}, --Mana
        Shaman = {26/255, 160/255, 255/255}, -- Mana
        Warlock = {26/255, 160/255, 255/255}, -- Mana
        Paladin = {26/255, 160/255, 255/255}, -- Mana
        MonkMistweaver = {26/255, 160/255, 255/255}, --How to check if monk is MW or not status: Unknown atm
        Mage = {26/255, 160/255, 255/255}, -- Mana
        DruidRestoBalance = {26/255, 160/255, 255/255}, -- Mana
        Warrior = {255/255, 26/255, 48/255}, -- Rage
        DruidGuardian = {255/255, 26/255, 48/255}, --Rage
        Hunter = {255/255, 128/255, 64/255}, -- Focus
        Rogue = {255/255, 225/255, 26/255}, -- Energy
        DruidFeral = {255/255, 225/255, 26/255}, -- Energy
        DeathKnight = {0.00, 0.82, 1.00}, -- Runic Power
    }
 
ns.cfg = cfg

Then at the top of the files where you need to access this information

local addonName, ns = ...
local cfg = ns.cfg -- if you want to save yourself some typing and reference the table as cfg.[i]KeyName[/i]. Otherwise you could just access the values using ns.cfg.[i]keyName[/i]

powerText:SetFont(cfg.font, cfg.fontsize, cfg.fontflag) would then work. It wasn't previously because the way you had the flags set.

The way I think of it is :
Config File

1. Get Access to the table accessible to the whole addon - (done by assigning it to 'ns')
2. Assemble the information I want to put into the table
3. Add the information to the table (ns.cfg = cfg)

Then in each other file you need to get that information.

1. Get access to the table (assigning it to 'ns' again)
2. [Optional] Assign the ns.cfg part of the table to a new variable to make typing out table references easier.
3. Use or change the information as required.

That is just the way I think of it for it to make sense to me and it is a very simplistic view of it. Phanx and others could probably go into more detail for you if you wished.