All I know is that I have several Eshopping postings on my account this month and in all cases they show up as a single line and no reference to bonus, nor name of merchant.

One with the 12x from Macys shows as:
ESHOPPING ON-LINE PURCHASE MILES 930

One from Bestbuy at only 1x shows up as:
ESHOPPING ON-LINE PURCHASE MILES 500

I have several others ranging from 12 to 560 miles earned from different merchants at different multipliers.
I don't see how AA has a way to separate any multiplier number.
And I don't think AA knows what the multiplier is nor even who the merchant is.

I believe the merchant decides how many miles that are willing to offer and they likely pay EShopping for each mile.
Basically - it is a discount they are offering.
When Macy's offers 12x special for one day - that is just a bigger discount. Say the merchants pays 2 cents per mile. Then on a $100 purchase, 12x is 1200 points,
Using my example of 2 cents (I have no idea how much they pay - maybe less) that is worth $24. So Macy's is giving you a 24% discount off $100.
Could be they select days to offer the big 12x - so that it doesn't overlap with some other promos they have.

For my CC purchases, I get two lines, examples:
CITI AADVANTAGE EXECUTIVE CARD PURCHASES - yes
CITI AADVANTAGE BONUS FOR AA PURCHASE - no (this is the extra 1X bonus for 2x) - this will not count
AVIATOR MC AA PURCHASES - yes
AVIATOR MC AA PURCHASE BONUS - no (extra 2x from 3x on Silver). - this will not count.
AVIATOR MC EVERYDAY PURCHASES - yes - these are for non AA ticket purchases.
CITI AADVANTAGE GOLD CARD PURCHASES - yes
CITICARD BONUS MILES - no - this was a special the Gold card had for 5x on groceries and gas.
SHELL BASE MILES - yes (fuelrewards)

Also - I might stay at a Wyndham hotel once a year - but I choose Airline points instead of Wyndham points:
So I have a recent posting:
WYNDHAM HOTELS AND RESORTS xxx miles

I would say this is another way to get AA LPs. Have hotels post miles to your AA account instead of their hotel program.