This lesson was originally written entirely theoretically, based on my own surmisings from Tolkien's work. Since the publication of Vinyar Tengwar #50 however, it looks as if my suppositions about 'aen' have turned out to be correct!
Future unreal = 'could', would'. Obviously we already have the basic conditional tense from the word 'If', so this is for more complicated sentences. This is an idea I had whilst thinking about the King's Letter, the longest Sindarin text, particularly the line i sennui Panthael estathar aen = 'who ought to be called Fullwise'.
Now, if we analyse this sentence, we see we have i = the relative pronoun, 'who' sennui = instead/rather Panthael = 'Fullwise' estathar = 'will be called'
And then we have aen at the end, which to my mind can only be to signify the conditional tense, changing estathar - 'will be called' into estathar aen - 'should be called'.
As I'm sure you're aware, aen is probably the most controversial word in Sindarin, every scholar has their own thoughts on what it means, and some prefer not to use it at all.
As the only example we have is for the future tense, I will not try and extrapolate it into other tenses. In the King's Letter, aen is shown to follow the verb, so here are some examples that follow in the same vein:
Medathon aen = I would eat Cenathol aen = You would see Istatha aen = He would know Telathon aen na i mar gîn = I would come to your house Aníratham aen lembas = We would want lembas