The green onions, lettuce and cucumbers are ok to plant together - all of them have a high nitrogen requirement.
Looks like you will run out of room with the squash. Allow at least 2 - 3 feet on each side of the squash plants for growth. With the right soil and fertilizer, those squash plants are going to get pretty big.
Squash needs a well balanced fertilizer, such as 13-13-13.
The raised bed is nice. What I suggest, next year build a raised bed based on fertilizer requirements.
Lettuce, onions and cucumbers go in one bed - all of them can use high nitrogen fertilizer, such as 21-0-0 or something like 16-6-12.
Tomatoes, squash and zucchini would go in the second bed - all of them use a balanced fertilizer, such as a slow release mature and something like 13-13-13.
Just about anything with large leafs is going to need more nitrogen then say tomatoes.
Keep this in mind when you plant your garden, lets take 13-13-13 as an example.
first 13 - nitrogen, promotes stalk and leaf production, such as corn, greens and spinach
second 13 - phosphate, promotes root production, such as potatoes
third 13 - potash, promotes pod production, such as peas, beans, squash.
Cucumbers require nitrogen to prevent them from getting a pointy end.
Looks like your project is off to a good start and keep up the good work.
