I just looked and found that in patch 2.16, you have implemented this:

When using signs to mark players, a message will now appear in the log window.
Which is quite excellent.

Now I would like to request that assigning a Waymark or cancelling a Waymark shows a message in chatlog, too.

Today I was in Syrcus Tower and someone was messing around with the Waymarks. No matter how many times I tried to put it (Waymark C for my team C) back to where it belonged, it got moved to other random spots, repeatedly. Someone else tried to battle against the troll and moved it back when I stopped trying, and the Waymarks were still going everywhere.

In many dungeons and against various boss enemies, Waymarks play a crucial role in helping the teamwork and strategies. For healers, Waymarks can indicate the general area where their party members should stay in the vicinity of, so that healers won't have range problem while healing them. For melee DPS, it helps immensely in marking the spot where a minion will appear, and sometimes where to gather during specific phase of battle.

To have people mess around with the Waymarks freely without being caught by the others had proven to be quite troublesome in my Syrcus Tower run today.

It would be extremely nice to show messages like "Aleczan cancels Waymark C" and "Aleczan assigns Waymark C" so that the whole alliance will witness who does it, and thus discourage troll or griefer, as they will be discovered immediately whenever they abuse the function.