I think there is a misunderstanding about the type of Birdy.

JRat had a Riese & Müller Birdy City, not a Pacific Cycles Birdy 9SP STD.

The Birdy City from Riese & Müller has a Shimano Nexus IGH and like all R&M Birdy it has a hollow crankset.

The 2019 TI Birdy has a totally different crankset, its a FSA SLK-Light with integrated axle. Its not possible to use spacers with this crankset.

And also, the Ti Birdy frame is totally different from the Birdy 3 frame. All frame dimensions are different, even the wheel base is different, its about 20mm smaller than the Birdy 3 wheel base (I have a R&M Birdy 3 Touring and a Pacific Cycles TI Birdy 2019 and compared the two frames).