The first person that I can find to tie Shigeharu (Hanbei) to Zhuge Liang was his son, Shigekado, who wrote the Toyokagami in the early 17th century. It's a fairly short biography of Toyotomi Hideyoshi. The much more well known Oze's Taikōki does not mention the man at all. And despite Shigekado being Shigeharu's son, he mentions his father by name exactly once in the Toyokagami. When Shigeharu died, writes his son, Hideyoshi mourned as Liu Shan did when Zhuge Liang died. There is exactly one other mention of Shigeharu before this, and only by association. In the summer of 1570, on Hideyoshi's request, the Takenaka, Makimura, and Marumo clans were transfered by Nobunaga to under Hideyoshi's command. So despite drawing a parallel between the deaths of Shigeharu and Zhuge Liang, Shigekado does not once tell us what his father did when he was alive.

The early 18th century Sōkenki is the earliest I could find that says he was an amazing strategist and commander in battle who passed down his knowledge to Hideyoshi. Yet this general description is all it wrote. It does not say which battle, which strategy, which command, or which knowledge.

The late 18th-early 19th century Picture Book Taikōki is the oldest source I've found so far to say that Shigeharu defeated Nobunaga when the latter was trying to conquer Mino (but does not put a name, date, or place to the battle). It's also the oldest I've found that said Hideyoshi went to ask Shigeharu in person to join them by pretending to be a travelling rōnin, a story repeated a few times in fiction published in Imperial Japan. But none of them really describe his contribution to any specific battle or campaign after joining Hideyoshi. Even in the picture book he shows up as a semi-important character only two more times after joining Hideyoshi, once talking to Hideyoshi's subordinates at a banquet, and once at his death.

At this point I'm kind of willing to bet that most of Shigeharu's concretely-stated contributions (and that Hideyoshi went to ask him three times like Liu Bei asked Zhuge Liang) came from the Yoshikawa Eiji's newspaper historical fiction written during WWII which was combined and published as Shinsho Taikōki after the war ended.