To type efficiently using the Gopika Gujarati Font Keyboard Layout, you do not change your Windows language to Gujarati. You keep your keyboard on English (US).
If you install Gopika and start typing without changing your keyboard settings, you will see Roman English letters (A, B, C...) but rendered as Gujarati glyphs. For example: Gopika Gujarati Font Keyboard Layout
This is the essence of the Gopika layout: The English QWERTY keyboard becomes a direct visual map to Gujarati consonants. To type efficiently using the Gopika Gujarati Font
However, the layout has significant downsides: This is the essence of the Gopika layout:
Most beginners assume Gopika works like "Google Phonetic" (Type "K" + "a" = ક + અ). It does not.
Gopika expects the Typewriter layout.