That’s not a Giyur Lechumra. If your mother was never born Jewish and only converted reform, then she is not Jewish. Reform conversations do not, and never did, contain Kabbalas Ol Mitzvos and are therefore invalid.
And yes, we treat someone who underwent Giyur Lechumra as a Ger for some things. I do not believe that we allow a woman who underwent Giyur Lechumra to marry a Kohen, for example.