A number of conditions could cause the small yield and browning leaves on your cucumbers and tomatoes. See the below link for information on cucumber problems. It includes photos that might help you identify the issue:

https://plantvillage.psu.edu/topics/cucumber/infos

If you determine that your vegetables have suffered from blight, you should replace all of the soil in the elevated bed in the spring; otherwise, adding about 1/3^rd new soil should be sufficient. A combination of potting soil and compost works well. Add fertilizer a week or so before planting your vegetables.

You might have more success with compact vegetable varieties, such as ‘Tumbling Tom’ tomatoes, in your beds. For more information about elevated garden beds, including several answered questions, see:

https://savvygardening.com/elevated-raised-bed-gardening/

This may be a good resource for you.

Remember to monitor soil moisture, and don’t let the elevated beds dry out completely. They are subject to sun and wind from all sides, unlike plants located in the ground.

We wish you a successful crop this year in your elevated beds.