New wall-hung toilet leak mystery

Dear Team
New wall hung toilet leaks from cavity at base after flushing. It starts trickling through after a couple of mins or so and continues for a while Original plumber bashed out tiles and resealed join. No joy. Second plumber removed toilet, realigned soil pipe, checked all connections and replaced. No joy here either. He felt one answer might be a crack ‘in the skin’. However, I just noticed that the downpipe from the cistern to the toilet is at a slight angle to the right. Could this be it? The toilet does not leak when flushed with a bucket. It has a push button flush on the wall. I don’t know the brand as the box has been thrown away but I believe it is Italian. Plumber coming again this week and I would be incredibly grateful for any more possible fixes he could try before having to send the toilet back. Would also be helpful to know if there is a way to find out if the fault IS with the toilet itself. I have a pic but it won't paste into post.
In hope
Caroline

toilet

IF the plumber is competent, then HE should be able to find the leak, regardless of what you tell him.

reply

I understand what you say but obviously this is proving difficult to diagnose as first plumb got it wrong and second is stumped apart from damage theory. We would probably get there in the end but if other people have solved a similar problem it would be good be able to benefit from their experience and cut down the cumbersome trial and error process. On the other hand I am completely ignorant myself and have no idea of the level of competence of my plumber and therefore any advice is even more valuable. If I am being unreasonable, please just ignore this post.
C

It could be quite a few different things... We could speculate from here but thats all it would be... A plumber on site needs to figure this out....

Now if you live in a choice vacation destination and are sending plane tickets...

I think it might be the tank-to bowl connection that is leaking.

Note that I am not a pro.