what other metrics can i use to estimate quality of the model predicting income range - interval estimation task?

I trained a model that predicts customer's income given the features:

• age, declared income
• number of oustanding instalment, overdue total amount
• active credit limit, total credit limit
• total amount

The output is a prediction: lower-upper bound for a customer: e.g. [8756-9230]

Metrics used:

• NIRDM - not in range distance mean - how far the value is from the closest bound (on average) for values out of range(similar to true negative)
• in-interval - percent of tested values that actually happen to be within the range(similar true positive)

e.g. NIRDM = 1.37, on avg values deviate by 0.37, less is better.

my question: what other metrics can be used to estimate the accuracy of the model.

I dont have deeper expertise on this 'range estimation task', maybe confidence interval?