Other posters are responding to your main question.
In the Latin Church the bishop reserves the right to confirm Catholics. There is usually an annual Mass prior to Easter when the Bishop will confirm all the adult Catholics from his diocese. The local parish, in our case the local Deanery (a group of neighboring parishes), holds a series of classes to provide teaching to these baptized, unconfirmed Catholic adults.
Your mom can talk with the parish priest in a Latin (“Roman”) Catholic parish about these classes, since her baptism was in that Church . Usually the Director of Religious Education for the parish would meet with her and explain the process in their parish. We have a number of unconfirmed Catholic adults in the Latin parish where I assist in catechesis, who have chosen to come to our ongoing RCIA classes and will soon switch over to the series of classes, about to begin, specific to preparation for their Confirmation. These classes are really a wonderful opportunity to share one’s faith journey with others. Your mom can sit in on a few to see what she thinks. Quite likely you could both attend together to see what you think.
The Sacraments/Mysteries of Initiation (baptism, chrismation/confirmation, and Eucharist) are all three done at once for unbaptized adults seeking Christian baptism in the Latin Church. In the Eastern Churches normally all three Sacraments/Mysteries are done at one time for persons of any age, infancy to adult.
She could seek chrismation/confirmation in an Eastern/Oriental Catholic Church but that would entail a formal change in her Church status from Latin to that EC/OC and would only come after some considerable time practicing her faith in that EC/OC parish. Becoming confirmed in the Latin Church would entail only the preparation for the annual confirming of that sacrament as mentioned above.
Also, I didn’t see anyone provide the link to
find-a-parish in your other thread “Catholicism vs. Eastern Orthodoxy”, in terms of looking for an Eastern or Oriental Catholic parish to visit. Websites are included there. Parish websites usually indicate the language used for Liturgy.
It’s great you and your mom are making these explorations together.