Have you verified that your transaction creation functions are working fine for other types of transactions and that it is just the TapScript code that's causing errors?
Yeah I have a more complex version of each script that creates the inscription address, I send a BTC transaction to that address, then the script spends the UTXO that I sent the address. The Javascript scripts works perfectly and creates an inscription when I spend along the script path of the freshly created address. The C# script fails with a signature error when I try to spend from the script path of the freshly created address.
My C# script works fine spending along the address keypath, but not the script keypath. Looking at the output transactions from the Javacript script and C# script, I've narrowed it down to the the tapscript not being created correctly in the C# script.