Not OP.
But one poll that still shows the majority against. And indicates a huge huge change in the younger voters over past polls.
Seems to fail to back up most out your claims.
You claim the young are not changing views as they get older. Unfortunately your one poll from march 25 is in no way enough to support that. When past polls all indicate it dose. Untill you have 2 or more polls over a longer period. All it shows is an increase in people of that current age groups.
Personally it is none of my business. As an Englishman I feel both Scotland and Wales should be free to do as they want. Only when they have the internal support to do so.
But your evidence is not enough to claim Welsh LD is making a mistake when all polling still shows a majority no with just one 1000 person poll showing a swing in under 35s.
There is a good reason parties tend to rely on poll of polls rather then single results.
A single 1000 person survey in a almost 3000000 population will always be at risk of anomaly.
Not to mention any poll funded by a group hoping for one answer. Needs very close analysis. They are not all bad. But it is very possible and common for such groups to alter questions and demographic requirements to paint their own picture.