You said there is "something wrong with the settings of my MySql". I asked how you inferred that. In response you posted my.cnf file contents. Well, what in those files leads you to think there is something wrong with your MySQL settings?
> I applied double the quotes trick to the entries that gave problems
What is a "double the quotes trick"?
Please post a SELECT result for the table row containing the column value
's-Heerenberg
Quote
I looked into the mysql error log and I found hundreds of entries like this:
[Sun Oct 07 18:40:46.234657 2018] [core:error] [pid 16752:tid 2856221504] [client 222.209.12.214:52567] AH00124: Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace.
That text appears to from a PHP or Apache error file.
To eliminate as many confounding variables as possible, please run this simple little test script through your mysql client ...
create schema if not exists testdump;
use testdump;
drop table if exists test;
create table test( str varchar(128) );
insert into test set str='\'s-Heerenberg';
select * from test;
... then exit the mysql client and run ...
mysqldump -uYUSERNAME -pPSWD testdump test
... (substituting your MySQL username & pswd) to ensure that mysqldump faithfully reproduces SQL for the test table. Then run the same script redirecting mysqldump to a file, and import that file to ensure that it's imported correctly. Let us know what happens.