It sounds as if there might be/might have been an issue with your baby's intake - this is not necessarily the same as 'a supply problem', as some mothers, especially in the early days, can make a lot of milk but if it is not getting into the baby then obv that's something that needs fixing.
You dont give details of your baby's weight and behaviour at the breast, and these are other important ways of assessing intake. The midwife who said your baby was not getting sufficient nutrition to grow properly may well have got the right info to make this assessment, and maybe she has observed your wife and baby feeding which would also help her.
Sorry if I am getting this wrong, but it sounds to me that you are wanting all this to be fixed by scheduling the baby, or by putting the baby onto a feeding routine, and this will just not work. Babies gain/catch up weight by increasing the volume of milk, by feeding more often. This can mean frequent feeding, day and night. This is not something that lasts forever, however - but of course it can be hard work while it does last.
I'm wondering if the consistent response you say you have had from the sources of help you have consulted have more or less said this - feed often, day and night, and accept that for the time being, your baby will need comfort and feeding and holding a lot, and will not like sleeping apart from his mum, and will cry after only a short time of being alone. You find this hard to accept because it is hard work - and you are looking for another solution.
There may not be another solution. This may what is needed at the moment to establish bf and to keep your baby comforted and growing.
I can see you don't always take to information that does not fit with your expectations - your scepticism about diet and bf is an example of this. You sneer at this because you find it hard to believe - and make a flippant remark about a mother being dead :(.
I think it is impossible that your wife will die of starvation. But if she is not eating well, or very often, her bf will not be affected. Her well-being may well suffer a bit, but the evidence in many studies, and indeed from what we know of biology, is that lactation is a physiological process that happens separate to the mother's own food intake. Just as you keep producing blood, and lymph, and spinal fluid, and continue breathing and moving, whether or not you are eating well, breastfeeding is largely unaffected.
Mothers do have variations in supply, and babies do have variations in needs. This need not mean bf is fragile, because the mothers whose production and storage 'system' is slower or lower can meet their babies' needs just as well - even when the baby's needs are great. A mother who produces smaller quantities of breastmillk will need to feed more often in the beginning, especially. This typically settles down after a while.
Whatever.....it has nothing to do with her own diet.