Hi Joho,
Citroen is right; may be all bogus marks; the date letter L or perhaps tax mark (smaller sized) for 1795 should look like;

An example for Amsterdam tax paid during the year of 1795

From left to right:
Amsterdam date letter D for 1788; Amsterdam city guild mark (upside down);
Small sized letter L, tax paid mark for Amsterdam punched in 1795; Crowned V for large items; duty mark.
Te date leter K should look like;

The Guild mark for the city of Amsterdam; looks like a dual punch mark used in Amsterdam for the designation of silver fineness of 2nd Standard. However the lion rampant indicates silver of 1 st standard, again perhaps a nice bunch of fake marks only to deceive the ignorant buyer?
Jan H. Middelhuysen 1778-1807; two known maker’s mark MH and M(dot)H. Citroen notes M(dot)H this mark can also be encountered as a falsification.
The Dutch lion rampant on your box does not really help to confirm right or wrong.
I found another set of marks with the maker’s mark of Jan Middelhuysen ; those look a little stronger but….

Perhaps you should consult some real reliable experts and ask their opinion.
Best,
Oel