How would I fix this old pre-written baseball bat code?

So a little backstory to give some insight about what this is. This is the main script in an older tool used for ROBLOX baseball. It is NOT my own script, but the community reached out to me since I know a fair amount of Lua, but I haven't played or kept up to date at all with recent ROBLOX updates, and the research I have done has left me confused and unsure of what needs to be fixed. I understand that they had to hinder the communication between server-side and client-side script to better prevent exploits, but I honestly don't know enough about Lua to know if that is what is causing this issue, or if I am just overlooking a small issue that is a simple fix.

Here is the script, I can do my best to interpret it if necessary if anything seems confusing since there isn't much context with just some lines of code.

--player
player = nil
--save shoulders
RSH, LSH = nil, nil
--grip
GRP = nil
--welds
RW, LW = Instance.new("Weld"), Instance.new("Weld")
--what anim
anim = "none"

--onselected, save shoulders and get player
script.Parent.Equipped:connect(function()
	player = game.Players:playerFromCharacter(script.Parent.Parent)
	local ch = script.Parent.Parent
	RSH = ch.Torso["Right Shoulder"]
	LSH = ch.Torso["Left Shoulder"]
	GRP = ch["Right Arm"].RightGrip
	--
	RSH.Parent = nil
	LSH.Parent = nil
	--
	RW.Part0 = ch.Torso
	RW.C0 = CFrame.new(1.5, 0.5, 0) --* CFrame.fromEulerAnglesXYZ(1.3, 0, -0.5)
	RW.C1 = CFrame.new(0, 0.5, 0)
	RW.Part1 = ch["Right Arm"]
	RW.Parent = ch.Torso
	_G.R = RW
	--
	LW.Part0 = ch.Torso
	LW.C0 = CFrame.new(-1.5, 0.5, 0) --* CFrame.fromEulerAnglesXYZ(1.7, 0, 0.8)
	LW.C1 = CFrame.new(0, 0.5, 0)
	LW.Part1 = ch["Left Arm"]
	LW.Parent = ch.Torso
	_G.L = LW
	--
	GRP.C0 = CFrame.new(0, -1, 0) * CFrame.fromEulerAnglesXYZ(-1, 0, 0)
	--Bring_Arm_Up animation
	for i = 0, 1, 0.05 do
		wait()
		RW.C0 = CFrame.new(1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(1.3*i, 0, -0.5*i)
		LW.C0 = CFrame.new(-1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(1.7*i, 0, 0.8*i)	
		LW.C1 = CFrame.new(-0.3*i, 0.5+1.2*i, 0)
	end
end)

--griptcf = CFrame.new(0, -1, 0) * CFrame.fromEulerAnglesXYZ(-math.pi/2+0.5, 0, 0)

script.Parent.Unequipped:connect(function()
	--Bring_Arm_Down animation
	for i = 1, 0, -0.05 do
		wait()
		RW.C0 = CFrame.new(1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(1.3*i, 0, -0.5*i)
		LW.C0 = CFrame.new(-1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(1.7*i, 0, 0.8*i)	
		LW.C1 = CFrame.new(-0.3*i, 0.5+1.2*i, 0)
	end
	RW.Parent = nil
	LW.Parent = nil
	RSH.Parent = player.Character.Torso
	LSH.Parent = player.Character.Torso
end)

function HomeRun()
	for i = 0, 1, 0.1 do
		if anim ~= "homerun" then return end
		wait()
		RW.C0 = CFrame.new(1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(1.3+1.2*i, -0.5*i, 			-0.5+i)
		--R.C0 = CFrame.new(1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(2.5, -0.5, 0.5)
		LW.C0 = CFrame.new(-1.5+0.5*i, 0.5, -0.5*i) * CFrame.fromEulerAnglesXYZ(1.7, 0, 0.8)	
		--L.C0 = CFrame.new(-1.0, 0.5, -0.5) * CFrame.fromEulerAnglesXYZ(1.7, 0, 1)
	end
	--start homerunhit connection--
	----------------------------------------
	for i = 0, 1, 0.2 do
		wait()
		RW.C0 = CFrame.new(1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(2.5, -0.5-1.7*i, 0.5+0.5*i)
		--R.C0 = CFrame.new(1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(2.5, -2.2, 1)
		LW.C0 = CFrame.new(-1-0.5*i, 0.5, -0.5+0.5*i) * CFrame.fromEulerAnglesXYZ(1.7, 0, 0.8-1.2*i)	
		LW.C1 = CFrame.new(0, 0.5-i, 0)
		GRP.C0 = CFrame.new(0, -1, 0) * CFrame.fromEulerAnglesXYZ(-1-2*i, 0, 0)
	end
	for i = 0, 1, 0.2 do
		wait()
		RW.C0 = CFrame.new(1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(2.5, -2.2-0.6*i, 1)
	end
	wait(0.1)
	----end homerun connection---
	--------------------------------------
	for i = 0, 1, 0.1 do
		wait()
		RW.C0 = CFrame.new(1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(2.5-1.2*i, -2.8+2.8*i, 1-1.5*i)
		--RW.C0 = CFrame.new(1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(1.3, 0, -0.5)
		LW.C0 = CFrame.new(-1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(1.7, 0, -0.4+1.2*i)	
		LW.C1 = CFrame.new(0, -0.5+i*2, 0)
		--LW.C0 = CFrame.new(-1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(1.7, 0, 0.8)
		GRP.C0 = CFrame.new(0, -1, 0) * CFrame.fromEulerAnglesXYZ(-3+2*i, 0, 0)
	end
end

function Whack()
	for i = 0, 1, 0.2 do
		if anim ~= "norm" then return end
		wait()
		RW.C0 = CFrame.new(1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(1.3+i, 0, -0.5+0.5*i)
		LW.C0 = CFrame.new(-1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(1.7-0.25*i, 0, 0.8-0.6*i)	
	end
	for i = 0, 1, 0.25 do
		if anim ~= "norm" then return end
		wait()
		RW.C0 = CFrame.new(1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(2.3-2.5*i, 0, 0)
		LW.C0 = CFrame.new(-1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(1.45-0.25*i, 0, 0.2)	
		GRP.C0 = CFrame.new(0, -1, 0) * CFrame.fromEulerAnglesXYZ(-1-0.5*i, 0, 0)
	end
	------
	for i = 0, 1, 0.2 do
		if anim ~= "norm" then return end
		wait()
		RW.C0 = CFrame.new(1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(-0.2+1.5*i, 0, -0.5*i)
		LW.C0 = CFrame.new(-1.5, 0.5, 0) * CFrame.fromEulerAnglesXYZ(1.2+0.5*i, 0, 0.2+0.6*i)	
		GRP.C0 = CFrame.new(0, -1, 0) * CFrame.fromEulerAnglesXYZ(-1.5+0.5*i, 0, 0)
	end
end

local last_click = 0
script.Parent.MouseClick.Changed:connect(function()
	if time() - last_click < 0.3 then
		anim = "homerun"
		last_click = time()
		HomeRun()
	else
		anim = "norm"
		last_click = time()
		Whack()
	end
end)

The part that I believe is causing issues starts at the function "Homerun" and continues to the end of the script. I know this isn't exactly an easy task though. I have spent a few hours on it and came up empty handed so far. Completely fixing it would be amazing, but it's an unrealistic expectation so any help would be appreciated!

Thanks.