How should the impairment loss be recorded in the financial statement and be viewed in context of evaluating past earnings and cash flow?

it's a decrease in the intangible assets value. An impairment loss is recognized through a journal entry that debits Loss on Impairment, debits the asset's Accumulated Depreciation and credits the Asset to reflect its new lower value.

Actually I could not fully understand your question, what evaluation you r asking for past earnings and cash flow. But what I know about impairment loss is as:

Impsirment loss shall be recognized only when there is significant and prolong decline in the value of an asset. Loss shall be recognized as per the nature of asset whether asset falls under IAS16 or under IFRS9 / IAS39.

I am not getting any idea how u r relating it with cash flows.