I have a similar piece of wood covered in anubias and java moss under 4WPG. No problem with the moss but because the leaves of the anubias stay around for a long time, they carry all the signs of past problems and tend to get some spot algae on them. In the same tank under 2WPG the anubias is spotless. So if you have yet to master your tank's nutrient balance, you may have some dirty anubias leaves to start with but eventually as you iron out any imbalances you should be able to maintain them relatively clean.
Hope that helps