Of your options, I really like:
[name_f]Isadora[/name_f] → intuitive way to the nickname and a lovely name - strong and elegant and bright too
[name_f]Elisabeth[/name_f] → classic and fairly intuitive – I’ve met an [name_f]Elizabeth[/name_f] ‘Izzy’, so why not [name_f]Elizabeth[/name_f] ‘Isa’.
[name_f]Anneliese[/name_f] → a pretty name, elegant and frilly, but [name_f]Isa[/name_f] adds a playful element
[name_f]Lois[/name_f] → lovely, warm name and I think [name_f]Isa[/name_f] works well
[name_f]Ines[/name_f] → sparky and international and [name_f]Ines[/name_f] ‘Isa’ works to me
[name_f]Louisa[/name_f] → classic, strong and literary – I think this makes sense as [name_f]Isa[/name_f] is the last sound 
[name_f]Cerise[/name_f] also came to mind