Your coffee plant does indeed look healthy and from the photo you included I do not see any brown spots on the foliage. My best guess is those spots are from low humidity most often caused by indoor winter heating. This houseplant likes bright light but not direct sun as  it is a tropical plant and when native the coffee plant grows under the shade of large trees. Another thought is that there is an insect called scale that appears as tiny brown bumps on the foliage. You can remove them by dipping a cotton swab in rubbing alcohol and touching each scale to dry it up. Then scrape off the shells and wash the plant every few weeks or use an insecticidal soap for six weeks as there may be tiny scale eggs that hatch. Keep growing, Marianne Binetti