Loft doesn't work - single surface merge

Hello! I am a beginner in grasshopper.
My intention is to rebuild the entire SudD form, to get rid of the lots of divisions, in order to pannalize the entire form in lunchbox. But i observed i need an entire merged surface, in order not to have every face of the surface divided.
Until know I have a problem with the loft component. I do not know what is wrong with the curves. Firstly they seemed to be closed, and the loft component announced me that i need open curves to loft. After this i tried pufferfish - “open curve”. They look like all of them to be open, by “close” testing, but smth happens in some places.
Can anyone help me please?
The big problem is how to convert the entire geometry into an only one clean surface in order to use it with lunchbox

Hi! Would the number of input curves to blame? In some other software I saw this leads to over-defining problem and make surface bad.

Upload the curves.
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