Calling another function inside a function and continuing it?

local Player = game:GetService("Players").LocalPlayer:WaitForChild("PlayerGui")
local Adventure = game.Workspace.Adventure
local Camera = workspace.CurrentCamera
local CameraPart = game.Workspace.CameraPart
local CameraPart = game.Workspace.CameraPart -- this is the Part we will move
local newPos = CameraPart.Position - Vector3.new(0,0,100) -- the position the Part will go to
local Time = 10 -- the time that the script will take to move the part
local Increment = 0.3 -- the Part will move 0.5 studs each time it moves
local Debounce = false
local Diff = newPos - CameraPart.Position -- the difference between the two positions
local Mag = Diff.magnitude -- the distance between the two parts
local Direction = CFrame.new(CameraPart.Position, newPos).lookVector


function onStart()
	Player.ScreenGui.Start.Visible = true
	Adventure:Play()
	wait(1)
	for i = 1, 100 do
		Player.ScreenGui.Start.GoodEnough.TextTransparency = Player.ScreenGui.Start.GoodEnough.TextTransparency - 0.01
		wait(0.01)
	end
	wait(5)
	for i = 1, 100 do
		Player.ScreenGui.Start.GoodEnough.TextTransparency = Player.ScreenGui.Start.GoodEnough.TextTransparency + 0.01
		wait(0.01)
	end
	wait(2)
	for i = 1, 100 do
		Player.ScreenGui.Start.Sacrifice.TextTransparency = Player.ScreenGui.Start.Sacrifice.TextTransparency - 0.01
		wait(0.01)
	end
	wait(5)
	for i = 1, 100 do
		Player.ScreenGui.Start.Sacrifice.TextTransparency = Player.ScreenGui.Start.Sacrifice.TextTransparency + 0.01
		wait(0.01)
	end
	wait(2)
	Player.ScreenGui.Start.Visible = false
	onScriptable()
	MovePart()
	wait(1)
	for i = 1, 10 do
		Player.ScreenGui.Idk.TextTransparency = Player.ScreenGui.Idk.TextTransparency - 0.1
		wait(0.01)
	end
	wait(3)
	for i = 1, 10 do
		Player.ScreenGui.Idk.TextTransparency = Player.ScreenGui.Idk.TextTransparency + 0.1
		wait(0.01)
	end
	wait(0.5)
	for i = 1,10 do
		Player.ScreenGui.Determination.TextTransparency = Player.ScreenGui.Determination.TextTransparency - 0.1
		wait(0.01)
	end
	wait(3.5)
	for i = 1, 10 do
		Player.ScreenGui.Determination.TextTransparency = Player.ScreenGui.Determination.TextTransparency + 0.1
		wait(0.01)
	end
	wait(0.5)
	for i = 1, 10 do
		Player.ScreenGui.Might.TextTransparency = Player.ScreenGui.Might.TextTransparency - 0.1
		wait (0.01)
	end
	wait(1.5)
	Player.ScreenGui.Might.TextTransparency = 1
	Player.ScreenGui.Start.Visible = true
	wait(1)
	Player.ScreenGui.Start.Chapter.TextTransparency = 0
	wait(0.5)
	Player.ScreenGui.Start.Unknown.TextTransparency = 0
	wait(5)
	Player.ScreenGui.Start.Visible = false
end

function onScriptable()
	repeat wait()
		Camera.CameraType = Enum.CameraType.Scriptable
	until Camera.CameraType == Enum.CameraType.Scriptable
	for i = 1, 1000 do
		Camera.CFrame = CameraPart.CFrame
		wait(0.01)
	end
	Camera.CameraType = Enum.CameraType.Custom
end

function MovePart()
	if Debounce then return end -- end the function if debounce is true
	Debounce = true -- make Debounce true so the function can't run
	for n = 0, Mag, Increment do
		CameraPart.CFrame = CameraPart.CFrame + (Direction * Increment)
		wait( (Time/Mag) * Increment )
	end
	Debounce = false -- set Debounce to false so the function can run again
end


onStart()

So my intention here is, while onStart is called, it will call onScriptable. However, I want the function to continue running after onScriptable is called, same when it calls MovePart. How do I do this? Thanks in advance.

From inside onStart, you can call spawn() where you want to call the function onScriptable like so:

function onStart()
	spawn(onScriptable())
	--Important code
end

function onScriptable()
	--Alternative code that needs ran at the same time.
end

More info here