I've been in the starts of talks recently with Petosa about a potential super bayan in C griff. During a conversation, they mentioned that their bass mechanics for converters are hand-made, by people paid hourly instead of per-mechanism, but mentioned that it could be an option to use bass mechanics that are more typical to what "most other manufacturers today" are doing, which were characterized as, if they break down, there's no real repair option other than to wholly replace (implying, but not stating (I didn't ask) that this isn't the case with the high-standard bass mechanics they would normally include. I was told that this option would not be available as a "Petosa" instrument, but that they would sell it to me as an "Americana" instrument.
This gives me the strong impression that Petosa and Americana instruments are manufactured at the same facility, and that they use the Petosa brand exclusively for instruments for which they did not have to compromise in any way from their most strictly ideal instrument - instruments to which they are "proud to affix their name", using the Americana branding for anything less.
Of course, this doesn't actually preclude them from using other manufacturing facilities for some subset of Americana instruments. Presumably even if they never do so now, but later bought another manufacturing facility, they would market all products built there as Americana (or perhaps some other non-"Petosa" brand), right alongside those other Americanas they may make themselves.
(Please do note that I'm not speaking from any actual knowledge of anything, only the impressions I have from a single conversation.)