manifests itself when I set lefthyphenmin and righthyphenmin.
Then sometimes sentences are to long. Would it not be better to
have a lot of whitespace between the words, but keep the
formating?

In the document the third line of the first paragraph is to long
and the fifth and sixth line from the second paragraph are to
long.

There is a problem with the formatting of paragraps. This

\setupalign[verytolerant,stretch]

I found also an obscure problem with table. I had to dabble a bit

to reproduce it. (For a moment I thought I had imagined it.)

The table does not fit on the space that is left on the page, so
it is moved to the next page. So far so good. But the text after
the table is put on the current page and is now before the table.

It is not that they can not be put on a page together, because
when you uncomment the break, the table and text reside on the
same page.

You are using \placetable which is a float. So, the table goes to the next page, but the material after that continues on the current page.

Lastly a question about a long click-able email address. I would

like it not to be broken up. But sometimes this can happen. See
the end of the document.(Can of-course also happen with a short
address, but will happen less often.) What is the best way to
circumvent this? At the moment I just put it centered on its own
line. At the moment I do not have a problem with this. But I do
not know if this will be always the case.

\setupinteraction[state=start]
\useURL
 [email]
 [mailto:quitealongusernametowriteanemailt@dummy.nl]
 []
 [\goodbreak\hbox{quitealongusernametowriteanemailto@dummy.nl}]