Learn English – The difference between disqualify and unqualify

Your examples are mixing two senses of the word challenging. The entry in Slovar-vocab is wrong when it states "stimulate" is a synonym of "challenge" when it means "something difficult".

1. The book I read stimulated me.
2. The book I read challenged me.

In sentence 1, the book is thought provoking or inspired interest in a topic.
In sentence 2, the language of the book was difficult and it took a lot of effort to read, or it forced me to confront my thinking about something and it was a little uncomfortable for me to realize that maybe I need to change my opinion or understanding. It's not clear from the context which meaning is the intended one.

One interesting thing to note is that while "stimulating" is sometimes listed as a synonym for "challenging", the opposite isn't usually true. They are only related through the word "provocative" which has two meanings:

1. Serving or tending to elicit a strong, often negative sentiment in another person; exasperating.
2. Serving or tending to excite, stimulate or arouse sexual interest.

"Stimulating" is provocative in a positive sense, but without necessarily the sexual connotation, like "exciting". "Challenging" can mean provocative in a negative sense, like "defiant" or "disturbing", but it usually means "difficult to do".

As with any good Chinese menu

Column A
Go
Look

Column B
Over
Through

The terms

have a look

means to see what is visible on the surface, not too much involvement

have a go (BrE)

means to try to do something, which mean more involvement

gloss over

means to superficially cover

plough through

means to use effort (to move dirt around, in the literal example)

In order of intensity of activity (one from column A, one from column B)

Look over
Look through
Go over
Go through

Arguably, in your dictionary sentences, one could say

Forensic ​scientists are going through the victim's flat
We're are still going through the ​details of the contract