You probably can automate the conversions you have described to some extent with an AppleScript but sorry that I don't know how.

Until you figure this or another automated solution you might use the following keyboard shortcuts in the given order to select multiple rows and copy & paste them in-place as values. These are likely to reduce the time you spend on such conversions if you are not already using them.

1. Go to the first cell in the last row you wish to convert to values,
2. Press Shift ⇧+Command ⌘+Right Arrow → to select all of the row,
3. Select as many rows as you like by pressing Shift ⇧+Up Arrow ↑ ,
4. When finished, copy all the rows by pressing Command ⌘+C,
5. Paste all the rows in-place as values by pressing Shift ⇧+Command ⌘+V.

You probably can automate the conversions you have described to some extent with AppleScript but sorry that I don't know how.

Until you figure this or another automated solution you might use the following keyboard shortcuts in the given order to select multiple rows and copy & paste them in-place as values. These are likely to reduce the time you spend on such conversions if you are not already using them.

1. Go to the first cell in the last row you wish to convert to values,
2. Press Shift ⇧+Command ⌘+Right Arrow → to select all of the row,
3. Select as many rows as you like by pressing Shift ⇧+Up Arrow ↑ ,
4. When finished, copy all the rows by pressing Command ⌘+C,
5. Paste all the rows in-place as values by pressing Shift ⇧+Command ⌘+V.