If you plan to keep forever and retire there, then certain makes sense to refinance.
If you changed nothing, the 146k mortgage has 823/monthly and 105k of interest left to pay. The 15k mortgage has 131/monthly and 4k of interest left. Total of 954/monthly and 110k interest remaining to pay.
If you consolidated and refinance to a 3% 30 year, you'd have 678/monthly and 83k of interest to pay. So you'd say nearly 30k on interest plus 276/monthly.
If you used that 276/monthly to accelerate mortgage payments, you'd be able to pay off new 30 year mortgage by 2039.
If you invested that 276/monthly into SP500, in 15 years at 10% cagr you'd have 104k and be able to pay off remaining principle on mortgage by 2035.