Right, I’ve calmed down now and am trying to take a fresh look at the whole situation and assess it. At first, I thought Google was mainly to blame. @NotHereToPlayGames believes that the owner and administrator @xper are solely to blame. The truth probably lies somewhere in between. Here is an alternative perspective on the whole matter from a very special source whom I am inclined to trust. I will not answer any questions about the nature of this source. It enjoys incognito status. So, believe it or not.
The cause: The "Japanese Keyword Hack" (or SEO spam injection)
The fact that Google search results display Thai characters or Asian text, even though the actual page is in English, is due to a security vulnerability in the forum software that was exploited by automated spam bots. In professional circles, this is usually referred to as the "Japanese/Thai Keyword Hack".
1. What the spammers did
Automated bots exploited a vulnerability on MSFN (often via the internal search function, registration pages or by generating thousands of fake profiles/posts). Unnoticed in the background, so to speak "invisible", they generated millions of artificial, low-quality URLs on MSFN, which were crammed with Thai terms, casino links, dubious diet pills or counterfeit branded products.
2. What Google did during the Core Update
Google crawled these hidden spam pages. As a Core Update re-evaluates the entire index, the algorithm noticed the sheer volume of this Thai spam content on MSFN. As these generated spam pages were highly optimised for the Google bot, the algorithm mistakenly assumed that the main topic or main language of certain forum sections was now suddenly Thai. In the search results, Google then mixes the page’s actual title with the injected Thai keywords from the cache, which is why the links look so strangely masked to you.
3. The consequence: Classification as a spam farm
Because the Google bot suddenly found millions of pieces of Thai spam content on MSFN, the algorithm pulled the emergency brake. Google classifies the domain at this point as "hacked" or "abused for spam". This leads to an automatic, algorithmic (or sometimes manual) block and a massive wave of de-indexing. In doing so, Google protects its users from suspected malware.
Summary for clarification
There is no malicious intent on Google’s part: Google does not “think” like a human. The bot simply sees: “Suddenly, 80% of all pages on this domain are Thai spam – so the entire domain is corrupted.”
It is not the intention of MSFN: The MSFN administration hasn't done much wrong; it has simply fallen victim to an aggressive, automated wave of hacking that exploited a technical vulnerability in the forum software to carry out illegal SEO sinking.
In practical terms, this means: Only once the MSFN administration, @xper and @Tripredacus, has completely removed all these fake URLs, profiles and injections from the server, closed the security loophole and sent a clean re-review request to Google via Search Console will the Thai characters disappear and the site slowly recover its position in the index.