A particular meditation wouldn't work in the setting I'm in - should I comment about that?

That may be a very constructive comment to make.

But please be aware that most of the meditations on this site will have been prepared with a particular congregation in view, and churches to vary. Literacy levels, how long people are used to listening for and the kind of employment people have all vary.

So, a speaker may post a meditation that leaves out much that could have been said in your setting. Conversely, a meditation may be more complex and involved than would be appropriate for you. Neither of those things is a criticism of that meditation, just a reflection of its contextualisation. Bearing that in mind, you may still wish to comment.