Conditional tense is when you use would/could/should. It’s used to speculate about what could happen, what might have happened, and what we wish would happen.
So, in my examples above,
Bydda’n mynd os ti’n mynd hefyd - I will go if you are going too
This is a “will happen” scenario, not a “might happen”/“could happen” one.
Byswn i’n mynd petaset/taset/'set ti’n mynd hefyd - I would go if you were going too
This is a “might happen”/“could happen” scenario, not a “will happen” one.
The “if” problem arises because in English there is no difference between a definite “if” and a maybe “if” - we just use “if” for both, so we don’t really take any notice of conditional tense. But in Welsh they are different which takes some getting our heads around because we’re so used to ignoring the difference in English!
Don’t worry Alan - we all get those, especially at the moment!