Hi Lukas Ley , you can also use the TerminologyManager singleton (https://developers.rws.com/studio-api-docs/api/terminology/Sdl.Terminology.TerminologyProvider.Core.TerminologyProviderManager.html?q=TerminologyProviderManager)

Example:

using Sdl.Terminology.TerminologyProvider.Core;

// Example URI for your termbase
string termbaseUriString = "file:///C:/Termbases/MyTermbase.sdltb";
Uri termbaseUri = new Uri(termbaseUriString);

// Get the terminology provider singleton instance
var terminologyProvider = TerminologyProviderManager.Instance.GetTerminologyProvider(termbaseUri);

// Ensure the provider is initialized before searching
if (!terminologyProvider.IsInitialized)
{
    try
    {
        terminologyProvider.Initialize();
    }
    catch (Exception ex)
    {
        // Handle initialization errors appropriately (log or surface meaningful error)
        throw new InvalidOperationException("Failed to initialize terminology provider.", ex);
    }
}

// Set up search parameters
var sourceLanguage = new CultureInfo("en-US");
var targetLanguage = new CultureInfo("it-IT");
string segmentText = "Insert your source segment text here";
int maxResultsCount = 10;
bool targetRequired = true;

// Perform a fuzzy terminology search
var searchResults = terminologyProvider.Search(
    segmentText,
    sourceLanguage,
    targetLanguage,
    maxResultsCount,
    SearchMode.Fuzzy,
    targetRequired
);

// Process or display results as needed...

Hi Patrick Andrew Hartnett , thank you for this option! I will try this to check if it applies the application settings for the fuzzy threshold.

One note on your code: terminologyProvider.Search() requires ILanguage instead of CultureInfo. I will try to construct a DefintionLanguage out of my CulureInfo to use it for the search. Please tell me if there is a more established approach

I tried to edit my answer but i am probably too late. Patrick Andrew Hartnett 

I added the Sdl.Terminology.TerminologyProver.Core dll to my project dependencies and I can get the TerminilogyProviderManager.Instance as you described.
Wwhen I try to get the TerminologyProvider for a termbase it throws a MissingTerminologyProviderException.

I get the paths from 

 List<Sdl.ProjectAutomation.Core.Termbase> termbases = SdlTradosStudio.Application.GetController<ProjectsController>().CurrentProject.GetTermbaseConfiguration().Termbases;
 
 foreach (Sdl.ProjectAutomation.Core.Termbase termbase in termbases) {
    if (termBase is LocalTermbase localTermbase && File.Exists(localTermbase.FilePath))
    {
        string filepath = localTermbase.FilePath;
    }
    
 }

Then i create a new Uri with each paths and try to get the TerminologyProvider. But then the excpetion is thrown.

I am developing a TranslationProviderPlugin if that matters? 

I tried to edit my answer but i am probably too late. Patrick Andrew Hartnett 

I added the Sdl.Terminology.TerminologyProver.Core dll to my project dependencies and I can get the TerminilogyProviderManager.Instance as you described.
Wwhen I try to get the TerminologyProvider for a termbase it throws a MissingTerminologyProviderException.

I get the paths from 

 List<Sdl.ProjectAutomation.Core.Termbase> termbases = SdlTradosStudio.Application.GetController<ProjectsController>().CurrentProject.GetTermbaseConfiguration().Termbases;
 
 foreach (Sdl.ProjectAutomation.Core.Termbase termbase in termbases) {
    if (termBase is LocalTermbase localTermbase && File.Exists(localTermbase.FilePath))
    {
        string filepath = localTermbase.FilePath;
    }
    
 }

Then i create a new Uri with each paths and try to get the TerminologyProvider. But then the excpetion is thrown.

I am developing a TranslationProviderPlugin if that matters? 

If anyboby reads this, I found a solution.

For whatever reason the TerminologyProvider URIs in the TerminologyProviderManager Instance do not start with "file". They start with "sdltb.file".
I have to admit I wasted a lot of time searching for this.

I am still on Studio 2024 (NOT SR1) so I dn't know if this is true for SR1 and later.

For a 'Sdl.MultiTerm.TMO.Interop.Termbase termbase' you can do 

Uri termbaseUri = new Uri(termbase.Information.Path, UriKind.Absolute);
Uri termbaseUriSdltb = (new UriBuilder(termbaseUri) { Scheme = "sdltb.file", Port = -1 }).Uri;
 var terminologyProvider = TerminologyProviderManager.Instance.GetTerminologyProvider(termbaseUriSdltb);