I can confirm the bug. The following constants are defined in the type library:

Const xlThemeColorDark1 = 1

Const xlThemeColorLight1 = 2

Const xlThemeColorDark2 = 3
Const xlThemeColorLight2 = 4

Const xlThemeColorAccent1 = 5

Const xlThemeColorAccent2 = 6

Const xlThemeColorAccent3 = 7

Const xlThemeColorAccent4 = 8

Const xlThemeColorAccent5 = 9

Const xlThemeColorAccent6 = 10

Const xlThemeColorHyperlink = 11

Const xlThemeColorFollowedHyperlink = 12

Const xlThemeColorDark1 = 1
Const xlThemeColorLight1 = 2
Const xlThemeColorDark2 = 3
Const xlThemeColorLight2 = 4
Const xlThemeColorAccent1 = 5
Const xlThemeColorAccent2 = 6
Const xlThemeColorAccent3 = 7
Const xlThemeColorAccent4 = 8
Const xlThemeColorAccent5 = 9
Const xlThemeColorAccent6 = 10
Const xlThemeColorHyperlink = 11
Const xlThemeColorFollowedHyperlink = 12

以下赋值按预期工作：

Const xlThemeColorLight1 = 1

Const xlThemeColorDark1 = 2 b
Const xlThemeColorLight2 = 3

Const xlThemeColorDark2 = 4

Const xlThemeColorLight1 = 1
Const xlThemeColorDark1 = 2
Const xlThemeColorLight2 = 3
Const xlThemeColorDark2 = 4

TinteAndShade仅适用于形状：

TinteAndShade only works for shapes:

ActiveSheet.Shapes（1）.TextFrame.Characters.Font.TintAndShade = -0.5

ActiveSheet.Shapes(1).TextFrame.Characters.Font.TintAndShade = -0.5