-- Lean 4 proof step from Mathlib.CategoryTheory.Triangulated.SpectralObject (goal)
Goal:
C : Type u_1
ι : Type u_2
inst : Category.{v_1, u_1} C
inst_1 : Category.{v_2, u_2} ι
inst_2 : HasZeroObject.{v_1, u_1} C
inst_3 : HasShift.{v_1, u_1, 0} C ℤ
inst_4 : Preadditive.{v_1, u_1} C
inst_5 : ∀ (n : ℤ), Functor.Additive.{v_1, u_1, v_1, u_1} (shiftFunctor C n)
inst_6 : Pretriangulated.{v_1, u_1} C
D : Type u_3
inst_7 : Category.{v_3, u_3} D
inst_8 : HasZeroObject.{v_3, u_3} D
inst_9 : HasShift.{v_3, u_3, 0} D ℤ
inst_10 : Preadditive.{v_3, u_3} D
inst_11 : ∀ (n : ℤ), Functor.Additive.{v_3, u_3, v_3, u_3} (shiftFunctor D n)
inst_12 : Pretriangulated.{v_3, u_3} D
X : SpectralObject.{v_1, u_1, v_2, u_2} C ι
ι' : Type u_4
inst_13 : Category.{u_5, u_4} ι'
F : Functor.{u_5, v_2, u_4, u_2} ι' ι
w w_1 w_2 : ι'
f : w ⟶ w_1
g : w_1 ⟶ w_2
⊢ Triangle.mor₁
        (Triangle.mk
          ((F.mapComposableArrows 1 ⋙ X.ω₁).map
            (NatTrans.app (mapFunctorArrows ι' 0 1 0 2 2 _proof_6 _proof_8 _proof_10 _proof_2 _proof_4) (mk₂ f g)))
          ((F.mapComposableArrows 1 ⋙ X.ω₁).map
            (NatTrans.app (mapFunctorArrows ι' 0 2 1 2 2 _proof_8 _proof_2 _proof_6 _proof_4 _proof_4) (mk₂ f g)))
          (NatTrans.app
            {
              app := fun (D : ComposableArrows.{u_5, u_4} ι' 2) ↦
                X.ω₁.map (F.mapComposableArrowsObjMk₁Iso (D.map' 1 2 _proof_2 _proof_4)).hom ≫
                  X.δ'.app (Functor.obj (F.mapComposableArrows 2) D) ≫
                    Functor.map (shiftFunctor C (A := ℤ) 1)
                      (X.ω₁.map (F.mapComposableArrowsObjMk₁Iso (D.map (homOfLE ⋯))).inv),
              naturality := ⋯ :
              NatTrans (functorArrows ι' 1 2 2 _proof_2 _proof_4 ⋙ F.mapComposableArrows 1 ⋙ X.ω₁)
                (functorArrows ι' 0 1 2 _proof_6 _proof_2 ⋙
                  (F.mapComposableArrows 1 ⋙ X.ω₁) ⋙ shiftFunctor C (A := ℤ) 1) }
            (mk₂ f g))) ≫
      (X.ω₁.mapIso
          (isoMk₁
            (Iso.refl
              ((Functor.obj (F.mapComposableArrows 1) (Functor.obj (functorArrows ι' 0 2 2 ⋯ ⋯) (mk₂ f g))).obj' 0
                homMk₁._proof_4))
            (Iso.refl
              ((Functor.obj (F.mapComposableArrows 1) (Functor.obj (functorArrows ι' 0 2 2 ⋯ ⋯) (mk₂ f g))).obj' 1
                homMk₁._proof_5))
            ⋯)).hom =
    (X.ω₁.mapIso
          (isoMk₁
            (Iso.refl
              ((Functor.obj (F.mapComposableArrows 1) (Functor.obj (functorArrows ι' 0 1 2 ⋯ ⋯) (mk₂ f g))).obj' 0
                homMk₁._proof_4))
            (Iso.refl
              ((Functor.obj (F.mapComposableArrows 1) (Functor.obj (functorArrows ι' 0 1 2 ⋯ ⋯) (mk₂ f g))).obj' 1
                homMk₁._proof_5))
            ⋯)).hom ≫
      (X.triangle (F.map f) (F.map g)).mor₁
have refine_1 : Eq (α := X.ω₁.obj (Functor.obj (F.mapComposableArrows 1) (mk₁ f)) ⟶ X.ω₁.obj (mk₁ (F.map f ≫ F.map g)))
  (CategoryStruct.comp (Y := X.ω₁.obj (Functor.obj (F.mapComposableArrows 1) (mk₁ (f ≫ g))))
    (X.ω₁.map (Functor.map (F.mapComposableArrows 1) (homMk₁ (𝟙 w) g sorry)))
    (X.ω₁.map (Iso.hom (isoMk₁ (Iso.refl (F.obj w)) (Iso.refl (F.obj w_2)) sorry))))
  (X.ω₁.map (isoMk₁ (Iso.refl (F.obj w)) (Iso.refl (F.obj w_1)) sorry).hom ≫
    X.ω₁.map (twoδ₂Toδ₁ (F.map f) (F.map g) (F.map f ≫ F.map g) sorry))
Tactic: dsimp