When working on marmara project where CCtxidaddr function is used a lot I got into issue with cc_conditionFromJSON function which returned NULL when I passed into it a cryptocondition with a public key created with CCtxidaddr (only some of CCtxidaddr pubkeys caused this error). Discovering showed that an internal function in secp256k1 library named secp256k1_ec_pubkey_parse actually failed on such pubkeys. So it could mean that some of the pubkeys created with CCtxidadds could be invalid. The pubkey in ECDSA algorithm is a point on the elliptic curve. As txid is created by a hash function that has nothing to do with ECDSA it could create values that are not on the curve.

There is a discussion here https://research.kudelskisecurity.com/2017/04/10/how-not-to-break-your-ecdsa/  whether it could be attacks on pubkeys that are not on the curve. It stated that such attacks seemed impractical but it is still advised to use valid key material in applications and check that the used points belong to the curve because this might prevent fault attacks (which is true in our case when a cc library json function fails on invalid pubkeys!). Simple tweaking of any single byte of a txid pubkey allows to quickly and deterministically obtain a valid pubkey. So I suggest making a new version CCtxidaddr_tweak() function and use it further.

I also checked the burn pubkey ("02deaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddead") which we use for burning tokens - it is also parsed as invalid. So we can tweak it too and get the valid constant burning pubkey.