About raids or high-level instances, there can be bugs, I couldn't say
Not to sound rude, but let me clarify... I'm not giving my opinion when I explain the bugs in the game. There are many threads easily findable on the current pages of the LOTRO forums discussing these issues. AND, of course, I'm experiencing them first hand in the game. I've provided both pro and con to the game. IMHO, the people to question are the 100% pro and 100% con as they tend to have an agenda.
That said, to answer the stable route issue... ALL of them are bugged. There is a chance that your ride will just stop at ANY point in the route. This is particularity frustrating on the non-swift routes as you can literally be stranded in the middle (which can be hostile territory that is difficult or at least very time consuming to get out of). Sometimes they work as intended... sometimes they don't. In my personal experience (playing every day) it happens about 50% of the time. You are then out the cost of the route and you are stuck somewhere you didn't want to be.
You may be lucky, and that is awesome if you are, but its not accurate to say the game is not very buggy.
The threads on the forums have moderator responses explaining they are working on the problem but are having problems identifying the issues. (same for the lag). You can also check the patch notes to see that they attempted a fix, but it did not work.
As for CD, yes, that instance was bugged for a couple of months. Entire instances in Moria were also shut down for a couple of months. In fact, a couple of months is the standard amount of time to fix anything because that is how often they "attempt" to fix things. When it breaks, its broken for a significant amount of time.... (unless its an exploit, those get fixed rather quickly).
I'll re-state, that I'm not trying to talk anyone out of the game. Aside from answering your questions, my comment was simply to TRY THE GAME, but do so with lower expectations and you might like it.