maximum amount of category listing at admin area

Hi,

There is indeed a limit of 200 categories displayed in the left explorer for the two first levels of categories. That's to avoid the page crashing because of too much memory used or the page being too slow to load.
What you can do however is to add an entry with the namekey explorer_default_depth and the value 1 in the hikashop_config table via your phpmyadmin.
That way, instead of 200 categories for 2 levels of categories, you'll have 200 categories for 1 level of categories preloaded on the explorer.
That should avoid the problem but it will mean it will do more ajax requests to load the sub categories.