As a translator, I strongly oppose this suggestion.
As far I can tell, transiflex is not free, neither in freedom (not free software) nor in price. The only thing that is “free” (no cost) is a 30-day test period. I do not want that. C:DDA is a free software project and it would be foolish if we start to depend on non-free software.
On the other hand, launchpad.net clearly has problems, I have to agree with you. But an alternative should be free (at least in freedom) and come with no strings attached. Transiflex is not one of these alternatives. Launchpad.net is based on free software, so theoretically someone with the (server) capacity could start an own Launchpad instance just for C:DDA. Maybe this server could be even more reliable than the big Launchpad.net server because there is not so much traffic. That would at least kill one of the downers, but not all. But that’s the best solution I can think of for now, sorry.
If launchpad.net is a serious problem for you, you can always fall back to this: download strings from launchpad.net, edit the .po file with your favourite editor, upload it back to launchpad.net again.
There is no dictionary(with project related words) for all languages
This is something which could go into our wiki. We don’t need extra software for this.
Edit:
I have done a little Internet search and found two Launchpad alternatives which are free software:
Pootle
I don’t know much about this one except that it’s a Launchpad alternative; More research on this one must be done.
Weblate
This one seems promising: Has strong Git integration. That’s great because C:DDA uses Git. Supports history. Translations can be commented. Comes with its own glossary/dictionary. I don’ know for sure how string downloads are done; I guess you use Git for it as well. Some advanced search criteria are available. I think this meets all of your criticisms to Launchpad.
I haven’t worked with any of those softwares, so I can’t assure you from experience that those softwares are actually good. Remember that those are just softwares, not servers, so someone has to set up a server and install the software. So something like a timeout problem should not happen if the server runs well.
I don’t propose anything now, especially when I don’t know much about the alternatives yet.
I just wanted to show that transiflex isn’t the only alternative and that there are also actual free software alternatives besides Launchpad. 