Oi! Welcome here!
Trisquel 7 runs great on my Positivo Sim+. The "Input Sources" tab of
"Region & Language" in the "System Settings" allows to manage keyboard
layouts. The "+" button in the bottom-left corner allows to add an
additional layout. You can order the layouts (the first one is the default)
using the two arrow buttons. Finally, notice the keyboard shortcuts to
"switch to previous source" (Shift+Super+Space by default) and to "switch to
next source" (Super+Space by default). Super is also known as the "Windows
key"...
With GNOME Shell, that I use, there also is an indicator of the layout in use
on the top bar. Clicking on it allows to switch the "source" (i.e., the
layout) and to display the current layout. That indicator is (was?) not
shown on Trisquel 7's default desktop but Mampir a solution, which is not
perfect:
https://trisquel.info/forum/trisquel-7-keyboard-indicator#comment-55540
As for the screen reader, it is automatically launched when you wait quite a
long time after the live system started. It is a feature: it allows blind
users to install Trisquel without any external help. Anyway, the screen
reader can be deactivated from the "Seeing" tab of "Universal Access" in the
"System Settings".
