I still haven't gotten this question resolved, I am afraid :(
Does adding this excess contribution to 'Other income' mean I paid tax on it (this excess contribution) in 2019 ?
Yes, if you removed the excess contribution, it is added to your taxable income. This is correct because it was not included in your taxable income W-2 box 1. The disallowed contribution is added back to your taxable income because it does not qualify as a tax-free contribution.