I don't know whether a thread like this is required for such a simple question. (Please read the forum rules
For example, you could have asked in this thread: COMMUNITY ADDON - Catalog Fixes for SE
Besides, it is not true. The star is in SpaceEngine, just not under the name 'Methuselah', but under its catalog names 'HIP 76976' or 'HD 140283'. (As far as I know, the name is also not official.)
The data of the star may not be completely correct, this is because the data in the Hipparchos catalog are a bit short.
(For some reason the names are not shown in the list in the search window, but SpaceEngine still finds the star.)
The planet 'Methuselah', which is a planet of the pulsar 'PSR B1620-26', is by the way also in SE.