Definitely, additional fertilizer is needed, excess water or not, given the way you are building your beds. Given all the extra rain water then granular/powdered ferts will work better than adding more liquids or foliar feeding.

Is there any danger to adding regular foliar feeds and handfuls of dried compost worked into top soil more often?

Not at all but the benefits would be minimal since you have only a minimally developed soil micro-herd to convert them to useable nutrients. Organic soil amendments like compost and manures are just that, soil amendments, not fertilizers. Without a highly developed bacterial herd to convert the nutrients in them the plants can't use them. And with new beds each year the soil bacteria are minimal.

Consider either adding large doses of micro- and macro-bacteria supplements each year or use granular/powdered organic fertilizers.

Dave

You can also make your own to have next year by starting a very active diverse-ingredient compost pile now so it is available to add to the plot soil much earlier next year. Of if you have year round access to the plot, sheet composting there.

6 weeks just isn't long enough to develop sufficient activity in the bed.

Dave

Therefore, in container gardening and also during and shortly after prolonged rains, it is mostly the nitrogen that becomes deficient as evidenced by yellow foliage. Under such circumstances I feed mostly Nitrogen, maybe some Potassium(K) but not much Phosphorous. If you cannot find those elements separately, use a fertilizer that is rich in nitrogen but poor in phosphorous with some potassium.

Also, I often just give nitrogen to my leafy veggies that you don't want them to flower and fruit. But K is essential for roots . Wood ash is an excellent source of potassium if you can get it.