IgorB:

Thanks GG/Phyllis, I tested very quickly in a fresh UbuntuStudio_16.04 installation on a empty hard disk to simulate without internet (offline). Seems to me it works fine. Wow! YOU ARE GREAT.
I had only one segv but without dump:
** segv at 0x7f9bd4107690 in pid 3425, tid 3425
(cinelerra-5.1-ub16-without-vaapi-x86_64-static_20190509)
no dump file has been created.
Tomorrow (Friday), I can test it better, if you give me more time, please.
Yeah! I think GG is willing to make a monthly build just for this purpose; kind of like the CinX build for OpenSuse.  But I do not know for sure yet. 

@Andrea_paz
For the Clear buttons, have you try to run cin with:
LANGUAGE="en_US:us" LANG="en_US.utf8" ./cin
please?
When I use the sister's notebook with UbuntuStudio_16.04 in Italian language I run Cinelerra-gg with that command. I don't know "LC_ALL=C
" command.

I can duplicate what Andrea has too.  GG is concerned about other locales too not having that symbol available.  He has some ideas but I am not clear on what he has yet.  gg/Phyllis