Based on this https://www.youtube.com/watch?v=O4FUZcF_IC4 video LeapRader seems to use similar technology in the sense that they both are based on grid of points with offsets. Although at least by eye the timing/anchor dots don't seem to match the exact scheme described in TipToi reverse engineering repo. Also didn't see any obvious Sonix chips in LeapReader, at least in the teardown pictures I saw.
Looking at the Sonix website (the company providing camera+decoder chip solution used by TipToi) https://www.sonix.com.tw/category-en-956 they seem to have at least 6 generations of the code with varying amount of encoded bits.
they seem to describe slightly different variations of data encoding. Searching for Anoto (company that made one of the first patents) leads to a bunch more products using this technology.
List of 400+ patents https://patents.google.com/patent/US6548768B1/en#citedBy citing the Anoto 1999/2003 patent also gives a list of companies working on related products or technology. There are even some from LeapFrog but those seem to mostly cover practical application and UI aspects of a product using the optical position/code detection system.
Overall feels like Anoto is focusing more on a system which decodes the points into X/Y coordinates and covers whole page with contiguous pattern, but Sonix more on having codes which give specific ID although they also one version which gives XY position similar to Anoto. That might be partially a workaround to make the encoding schemes different enough not to infringe each others patents.
That doesn't really give a good answer to your question, but If I had to guess Leapfrog is probably buying their technology somewhere else possibly from Anoto.
There is also one similar product using Grolier name, which seems to use tech from Sonix just like TipToi so potentially compatible, at least the codes not necessarily the book format.
Looking at the Sonix website (the company providing camera+decoder chip solution used by TipToi) https://www.sonix.com.tw/category-en-956 they seem to have at least 6 generations of the code with varying amount of encoded bits.
Some of the related patents https://patents.google.com/patent/US6548768B1/en (Anoto ~1999/2003) https://patents.google.com/patent/US8061611B2/en (Canon ~2006/2011) https://patents.google.com/patent/US20070246547A1/en (Sonix ~2006/2009) https://patents.google.com/patent/US10614333B2/en (Sonix ~2015/2016)
they seem to describe slightly different variations of data encoding. Searching for Anoto (company that made one of the first patents) leads to a bunch more products using this technology. List of 400+ patents https://patents.google.com/patent/US6548768B1/en#citedBy citing the Anoto 1999/2003 patent also gives a list of companies working on related products or technology. There are even some from LeapFrog but those seem to mostly cover practical application and UI aspects of a product using the optical position/code detection system.
Overall feels like Anoto is focusing more on a system which decodes the points into X/Y coordinates and covers whole page with contiguous pattern, but Sonix more on having codes which give specific ID although they also one version which gives XY position similar to Anoto. That might be partially a workaround to make the encoding schemes different enough not to infringe each others patents.
That doesn't really give a good answer to your question, but If I had to guess Leapfrog is probably buying their technology somewhere else possibly from Anoto.
There is also one similar product using Grolier name, which seems to use tech from Sonix just like TipToi so potentially compatible, at least the codes not necessarily the book format.