Bishop Devery is apparently not the bishop of the ward where the Henricksons live (S2, Ep 5 "Dating Game"). As such, he would likely not even participate, let alone conduct, Barb's disciplinary council.
Each person entering an LDS Temple needs his/her own Temple Recommend, which is examined and returned to the person by the attendant at the front desk. As such, it would be virtually impossible for Barb to "borrow" her mother's (or sister's) recommend, and then have both of them accompany her into the temple.
There is no time limit set on prayer and meditation in the Celestial Room of LDS Temples (nor does anyone keep track of how long people stay). As such, temple workers would never conceivably say, "I'm sorry, but your fifteen minutes are up."
According to practices of the LDS Church, the Bishop and Stake President wouldn't know how long Barb had not paid tithing. Financial records at the ward level are only kept for three years and then destroyed. Bishops typically serve for about five years, so it is therefore unlikely that this would even be the same bishop that she had seven years earlier.
To any active Latter-day Saint, the phrase "take [out] my endowments" indicates that the person is going to attend the temple for the very first time. This is known as a "live endowment." Subsequent visits to the temple are made in order to perform proxy endowments for a deceased individual, usually a relative. Although it's possible to borrow a Temple Recommend, a live endowment is a more complex process than a proxy one, and there is really no way that someone could perform a live endowment without the temple workers being fully aware of this. Therefore, depicting Barb secretly "taking" her endowments with her mother's borrowed Temple Recommend is contradictory.
Despite the fears that Barb expresses (and the title of the episode), The LDS Church does not teach that excommunicated members will (necessarily) be sent to Outer Darkness. Excommunicated members are actually encouraged to remain close to the Church and be re-baptized when the time is right.