"He always comes at this time."
Translation:Il vient toujours à cette heure-ci.
I think the problem lies in that without -ci, the sentence would become very ambiguous. It could make it mean "He always comes at that time." or "He always comes at this time," both of why are very different semantically.
-ci = this/these/latter
-là = that/those/former
I wrote "Il vient à cette heure-ci toujours" and it was marked wrong because of the position of the adverb. Native speakers, is it REALLY taht wrong to put "toujours" at the end? It isn't so in Spanish... "Él (siempre) viene (siempre) a esta hora (siempre)". Each one of these 3 placement options are completely correct and natural in spanish.
Yes, it sounds really weird/wrong to put it somewhere else in this sentence.
Nothing particularly wrong with the English sentence, as Dawnofdusk has already mentioned.
As to why "à cette heure-là" is accepted for "at this time", I'm not a Francophone, but from several other discussions on DL, I gather that in conversation, people commonly use "cela" and similar expressions much more frequently than they use "ceci", etc., even when "ceci" would be more strictly correct, and that they pretty much only use "ceci" when making a specific distinction: "Je veux ceci, pas cela".
"-ci" is more of a suffix that specifies that the preceding "ce" means "this" (as opposed to -là, which specifies that the preceding "ce" means "that"). You have to think of "ce" as a general pointing word rather than "this" or "that".
obitow above also posted a link: http://french.about.com/od/vocabulary/a/suffix-ci.htm
I realize you wrote this a while ago, so you may already have your answer, but just in case:
In English, we use the word time to mean a lot of different things: the concept of time, the time on the clock, and an occurrence (this time, three times, one more time, etc.) In a lot of other languages these concepts have distinct words, and French is one of those languages.
The concept of time/time as abstract: temps (e.g. It takes a long time, I don't have time)
Time on clock: heure (e.g. What time will you be here?, He always comes at this time)
Occurrence or instance: fois (e.g. his third time, one more time, last time, next time)
I hope this helps :)
Note: I studied French for a long time and lived in France for a while, but I am not a native speaker, so if any native speakers disagree with my explanation, please defer to them. Thanks :)
A related comment from Sitesurf, explaining why the suffix "ci" is required for this sentence: