The quorum of one-third of each House to be able to vote on any issue, is in a different category. That one is in the Texas Constitution, so it is beyond the power of the legislature to change it. Only a proposed and ratified constitutional amendment could get rid of that requirement.
Hence, you have the effort of the Senate -- and later the House if the Democrats play tag-team obstruction and the Senate Dems come home as the House Dems skedaddle -- to use fines and other disciplines to punish the missing members. These are matters of internal discipline in each House, and under normal circumstances they are no business of the courts. (Federal courts have long since recognized that sort of autonomy for internal Senate and House discipline in Congress.)
However, I wouldn't count heavily on the Texas courts, because the judges are all part of the raise-trial-lawyer-money-and-get-elected process. So the Texas courts might not be as protective of their constitution as the federal courts are of the US Constitution. (And, yes, I recognize that amouonts to d*mning with faint praise.)
John / Billybob