According to Wikipedia's article
https://en.wikipedia.org/wiki/First_Battle_of_Sirte, Italian aircraft identified the merchant ship Breconshire as a battleship.
The two reports from RAAF Hudsons of Mikawa's force before Savo Island were slightly misleading. The first had 'three cruisers, three destroyers, two seaplane tenders or gunboats' and the second 'two heavy cruisers, two light cruisers and one unidentified vessel'. This was taken to suggest that Mikawa's force was aiming to set up a seaplane base and focused the attention of the Allied cruisers on the sky.
By contrast, the Japanese aircraft finding Lee's force before 2nd Guadalcanal were almost accurate, reporting two heavy cruisers and four destroyers. However, Kondo was to discover that the two heavy cruisers had surprisingly powerful guns.
Finally, it is helpful when the staff processing reports remove 'speculation'. An article on the Battle of North Cape
https://www.historyonthenet.com/battle- ... north-cape has:
Bey had indeed received a report of the flying boat sighting but it was shorn of a crucial detail that, had it been included, Dönitz was later to claim could have altered the whole course of the drama. At 11:00 a.m. he had been told that five warships had been seen far to the northwest of the North Cape. The original report had included the information that one of the vessels was “apparently a big ship.” The senior air officer removed this detail before relaying it to naval headquarters on the grounds that he did not wish to pass on what he regarded as conjecture.
