Slitherine

I have recently played the multiplayer scenario (Erik - Midway 6.3) as both the Japanese and as the Allies. It seems that the scenario objectives combined with map size and range of the Aircraft leads to almost fixed outcomes against competent players.

The Japanese can easily meet the 2 US carriers sunk objective by launching all A/C as soon as they are located. Hint they will be as far east as the allied player can get them heading towards the exit grid. Defending the troop transports from Allied A/C is almost impossible against a competent Allied player, so the invasion of Midway will not happen even if the entire Allied fleet is sunk. The map size and the current starting location as one large transport fleet combined with land based bombers out of Midway makes discover just a matter of time. Once discovered the transports are fish in a barrel. Having learned this lesson in a previous game, I split the transports into smaller groups, sent out fighters from the Japanese CV's to reduce the land based aircraft impact, but ultimately that only slowed down the inevitable.

The Allied player can stop the invasion of Midway by finding and sinking the troop transports. Just launch all A/C as soon you you feel comfortable, use Midway as a refuel point if needed and sink the transports. Game over, except you need to wait until turn 34 even if this objective is met much earlier. Scoot your carriers to the exit point and hope your enemy is caught unaware. Japanese CV's are not important.

In the actual events the US had better intelligence and knew that the Japanese were heading to Midway. This allowed them to catch the Japanese CV's reloading bombers (got Lucky in this regard) and in a matter of a few hours sunk four Japanese fleet carriers. The troop transports were never targets.

So how to balance the scenario? Not sure you can modify carrier based plane range, but if you could reduce range from 14 to 9 or even less then it might require the CV's to move closer before launching search aircraft and then strike aircraft. This might then force a CV against CV battle more in line with the actual battle.
The other option might be to break up the Japanese transport fleet into smaller task forces and spread out over the map. Perhaps enlarging the map would help by creating more space to be searched? Do both? Modify objectives to force CV battles?

Fun scenario but the outcome is pretty much inevitable as currently organized.

Competent players that are familiar with the historical battle or have played the scenario before will no doubt find a strategy that works for either side.
As you have found.
The battle of Midway was won due to two issues; better US intelligence and more important, plain US luck.
The Japanese decision to switch from AP to HE bombs just as a few US dive bombers arrived turned the tables on the Japanese.

The latest editor has a provision for exchanging the pre-deployed units with purchased ones. This should add a lot of uncertainty to naval battles.
Unfortunately, it looks like your whole force needs to be undeployed/purchased. That means a lot of manual work in the deployment phase.
I would prefer to let the player cash in as many or few units as he chooses.

Anyway, I will add this option to all my naval scenarios as unpredictability was a major feature of the carrier battles.

Thanks for your thoughts.

I think the unpredictable is what will make these fun. I would like to buy my force and not be saddled with commanders decisions made in real world not the game world we fight in.

There is an option in the editor to customize your force, but I have not gotten it to work.
I don't know if it would force you to purchase your whole force or allow you to replace selected units.