The phrase "as I learned later" is correct and usable in written English.
It can be used to indicate that the speaker gained knowledge or understanding about something after the initial event or statement.
Example: "I thought the meeting was scheduled for Monday, as I learned later, it was actually on Tuesday."
Alternatives: "as I discovered later" or "as I found out later".
As I learned later, this was not just the predicted earthquake.
As I learned later, that idea could be extended to other aspects of the town, including its population.
It sounded mean and threatening, which, as I learned later, was the opposite of how you would describe the man.
Having been slightly ill, as I learned later, he had spent the day in his room, and now seemed restive.
As I learned later, such discussions are important; in medicine, they can be a matter of life and death.
They are actually things that start from almost nothing, or from — as I learned later — a rhythm here or a word there or a proverb somewhere.
It was delicious to eat as well — until I learned later that the federal government recommends that women who are pregnant, or who may become pregnant, not eat swordfish because of mercury contamination.
Mallory says that, before he had ever met Sigoloff, "the first written word about Sandy I read was a 1974 article in Business Week" that referred to his reputation as a "hatchet man". "I learned later that that was far from the truth". At Daylin, Sigoloff earned the nickname "Ming the Merciless," after a villain in the Flash Gordon serial.
Instead, I encountered a bald, long-nosed whippet of a man -- 76 years old, I learned later -- as tightly coiled as a sprinter, wearing gold-rimmed aviator glasses, running shoes, tan trousers, a blue blazer and a smile that lit up the room.
"There was nothing I learned later on as a college or pro player that he had not already exposed to me.
(The word critic, as I learned much later, comes from the Greek word for "judge").
