cpoohee:

E/tflite  (27736): Op type not registered 'CaseFoldUTF8' in binary running on localhost. Make sure the Op and Kernel are registered in the binary running in this process. Note that if you are loading a saved graph which used ops from tf.contrib, accessing (e.g.) `tf.contrib.resampler` should be done before importing the graph, as contrib ops are lazily registered when the module is first accessed.
E/tflite  (27736): Op type not registered 'RegexSplitWithOffsets' in binary running on localhost. Make sure the Op and Kernel are registered in the binary running in this process. Note that if you are loading a saved graph which used ops from tf.contrib, accessing (e.g.) `tf.contrib.resampler` should be done before importing the graph, as contrib ops are lazily registered when the module is first accessed.



So you have two operators that need to be inserted. Currently, tensorflow-lite-select-tf-ops:2.5.0 only contains a subset of selected TF ops. You can refer to this page 2 for detailed ops.
There is also this web 4 link when there are instructions about TensorFlow Text and SentencePiece operators where you can see these two ones that you use.
I asked you to send me the file so I can give a try to this Colab notebook 1 where you can build select-tf-ops.aar file from a .tflite model with special ops. If you give it a try inform us of the result when you import it inside android or flutter. If you cannot make it work ping me again. Pay attention to the last info where you have to download and place a custom .sh file inside tensorflow directory. Also use less target_arch let’s say ‘arm64-v8a,armeabi-v7a’ as this procedure takes a lot of time. (Of course do not use the other build bazel commands that create Support libraries  ).
Best