Just a thought Tom but are you over-watering? My rule of thumb is not to water until the soil at the top feels dry. For tomatoes, once they've hatched I wouldn't expect to water them at all for a week or two weeks at least.
That said, pissed off as I forgot to plant any this year.
I reckon that'll it be then. No way should they need watering every day until they get really big and bushy and then you might have to water twice a day ! I'm no expert but if you follow the same rule about checking how damp the soil is I reckon you'll be fine.
Also, if a seedling hasn't done anything at all (hasn't moved) for days on end its probably unfortunately a gonner.
Got these as plug plants on the first week in April, got fruit on some of the trusses now.
Tha'ts really nicely arranged. I got my plugs from ebay which arrived a few days ago. Normally do it from seed but started so late this year. Might have to try some set up like that with the canes etc. Mine end up getting bushing and going all over the place despite trying to snip out the extra shoots that appear between stems.