German keyword research should begin with the language people type, not with a translated English keyword list. Umlaut and non-Umlaut forms can represent different query patterns, and compound nouns, abbreviations, formal wording, and regional terminology can change the intent behind otherwise similar phrases.
Decision rule: compare the variants relevant to the page, then select the primary form that best matches the target audience and the search task. The data should guide the choice between forms such as "München" and "Munchen" rather than a blanket rule that one spelling must always be used. Secondary variants can appear naturally where they help users, but the main title, heading, and copy should remain linguistically coherent.
Also validate whether a term carries the same commercial meaning across the DACH market. A word used for a profession, service, product category, or legal concept in Germany may be understood differently in Austria or Switzerland. Record the country, audience, query intent, preferred wording, and page destination for each keyword before content production begins.