shall i create custom Taxonomies including the sub and subsubcategories?
or
is it better to build forms and search filters with every category by itself...
CATEGORIES ... is one new standalone TAXONOMY
->subcategories is one new standalone TAXONOMY
-->>subsubcategories is one new standalone TAXONOMY
not building sub and subsub in one custom Taxonomy
Is there any documentation that you are following?
no
Is there a similar example that we can see?
yes here hidden link
What is the link to your site?
you cannot see anything there it is under developement