I could definitely see Galtieri encouraging mainland Argentines to settle on the islands. Plus making the English speaking population learn Spanish but this is all my speculation. So what plans did they have?
Wrote several papers on The Falklands War in university.
The Argentinians did begin some changes during the occupation, keeping in mind that the occupation itself lasted under 80 days. They started altering traffic systems and forcing vehicles to drive on the right side of the road. They of course also altered existing signage to Spanish and over to metric where applicable. Radio stations and newspapers were taken over and/or disbanded.
Honestly, there doesn't seem to be much documented about the long term plans for the islands other than the immediate goal of integrating The Falklands into Argentine sovereign territory. It's important to remember the invasion was a reactionary measure to building domestic pressure on the junta.
There's no indication that there was a deliberate attempt to encourage Argentine emigration to the islands, but the efforts observed during the occupation are definitely indicative of a policy to make the islands more Argentine and less British culturally.
Hope this helps, feel free to reply with any other questions you have as I love discussing the Falklands War.