First of all this post is a joke and dont treat it as advise. Tax evasion is illegal.

In Germany, for a long time you could write-off bribes made in foreign countries as a tax expense. It was handled just like any other expense (e.g. telephone cost goes to "telephone costs" account, bribery went to a "bribery costs" account). Also you had to provide some proof that the bribe was actually made. It was ok to cheat foreign countries by bribing their officials or bribe purchasers from other countries to purchase your stuff, but it was illegal to cheat the state of Germany by making a non existant tax expense (for a non existand bribe). After EU was formed this practice became illegal

For the rest of your question, SAP allows you to keep multiple ledgers. One ledger can be official, others unofficial. Those ledgers are conceptually something like "views". Some managers look at different stuff.
For example you can have one ledger ("view") done as per local accounting regulations, another as per US GAAP, another per international accounting standards, another just to calculate local tax.. and yes "local tax ledger" is often different than "local bookkeeping ledger" (mostly different way depreciation is calculated).
Why would you make self incriminating evidence I dont know. Probably you are sarcastic. But usually the cheaters misclassify stuff in their books (e.g. revenue recognition - like Enron), or not show it at all (e.g. financial derivatives). I saw also something made of nothing (inventory movements that increased value).

Employee theft is just generic FI-AA accounting. When you have many employees sooner or later someone will steal something valuable that the company kept on its books (say an expensive laptop). Other thing is if you catch them.

If your company stole something, you can supposedly just recognize it as unusual gain and pay tax on it. I am not a lawyer so I dont know if your corpotation can go to prison ;), but some say that the tax office wont care if you paid the tax on the stolen goods (this is not tax advise). I heard about a construction company that got some tools from other company (that didnt want it back - they were shipped far away) and they just recognized it. Not sure how the other company dealt with it, sounds like criminal negligence. But maybe they didnt write it off from tax point of view. Was just a cost of running business that ate their result, but not a cost that decreases tax.

I heard that corruption is just handled by giving a bonus to the sales person. Then the sales person just cashes it out and uses this cash as a bribe. Of course such practice is illegal in civilized world. Also illegal if your parent company is in civilized world - they will even make you take those obligatory trainings about that.

If you are interested in reading about tax crime then search for articles about samen dividend used multiple times to change tax scandal. What has the very unfortunate name "cum-ex" ( https://en.m.wikipedia.org/wiki/CumEx-Files ). Some argue that the practice was legal in Germany for many years. Some say it wasnt.

Also you can read about money parked in Bermuda, Irish sandwich, treasure islands... many of those big companies seem to do those tricks.

Those arent related to the software you use