'Would it were true' or 'would that it were true' was widely used in 19th century speech and literature - mostly in a romantic way.
A 'would that it were' type of phrase is used in this extract from a poem, 'Lucinda', by Arthur Griffith.
''Oh! Lucinda!
My beaming, gleaming star,
I would that I were good enough
To dwell in dear Rathgar.''
LRV
Edit: 'Would it be so' - This is unfamiliar to me. I can understand 'would that it were so'.