Here are some options:
For "forever":
* Am byth: This is the most common and literal translation.
* Yn dra-byth: This emphasizes the "forever" aspect and means "truly forever".
* Tra bydd y byd: This means "while the world lasts" and implies a very long duration.
For "always":
* Bob amser: This is the most common translation for "always".
* Yn gyson: This means "constantly" or "regularly".
* Yn fythol: This means "everlasting" and emphasizes the continuous nature of something.
Combining "forever" and "always":
* Am byth a bob amser: This combines the most common translations for "forever" and "always" and is a good general option.
* Yn dra-byth ac yn gyson: This emphasizes both the "forever" and "always" aspect and uses more formal translations.
* Tra bydd y byd a bob amser: This combines "while the world lasts" with "always" for a more poetic and grand expression.
The best way to choose the right phrase depends on the specific context and the desired tone.