Thanks for you mention the potental solution.
I read the post you post before, it kind works for me but it have some issus mentioned up ward.
https://discourse.mcneel.com/t/multipipe-gives-sharp-spikes/171048/12
I don’t know weather the develper intened write mutiltpipe function like this or this is a bug. But i do think is possiable to rewrite the function to avoide this issus. instead of try to use grasshopper find the spiky vertices and remove it rewrite might be easier.
hope somebody can figuer it out.
thanks.