It's a really poor show that as far as I can see not a single source has provided a detailed breakdown of how the seats were won, therefore not showing how close a number of contests were.
Take Sir Gaerfyrddin: for the 6th seat the Reform vote share was 32.8 / 3 = 10.93 for Plaid it was 43.1 / 4 = 10.78
For Pen-y-Bont Bro Morgannwg for the 6th seat Labour had 11.6 to Plaid's 11.17
For Caerdydd Ffynnon Taf the Greens had 10.2 to Reform 9.8, Tory 9.6, Lib Dems 9.6
In Casnewydd Islwyn Tory 11.4 Reform 10.97
In Blaenau Gwent Caerffili Reform 11.43 Labour 11.1
In Pen-y-Bont Bro Morgannwg Labour 11.6 Plaid 11.17
In Bangor Mon Conwy Conservative 12.4 Plaid 11.23
In Clwyd Reform 10.77 Labour 10.4
In Fflint Wrecsam Labour 12.2 Reform 12.07
So that's 3 seats Plaid were within half a percentage point of winning. With those 3 extra seats they could have done deals with Lib Dems and Reform (combined).
Reform narrowly win and lost three seats each. Labour 3 narrow wins to 2.
8 constituencies were decided by less than half a percentage point. Slightly fewer than my prediction.