PHP (and others) "Go to definition/implementation" via LSP, not gtags/ctags
I'm not sure whether it is supported in SpaceVim for other languages but for PHP definitely the only way to find reference/implementation/definition is gtags which does not understand the code in a way to hide unrelevant entries.
For functions with common names such as 'count', 'find', 'getId' it is almost useless as the number of found results could be quite large especially including those from /vendor/ folder of the PHP project.

Probably if it's working the same way also for example for JavaScript/TypeScript - it should be a catastrophe as the number of libs in '/node_modules/' directory is usually enormous.

Spacemacs is using LSP to find references or interface implementations. So it should actually be somehow possible for Spacevim as well.

There is a chance that it would be alittle simplier for neovim with it's built-in LSP. I mean maybe there is an option to implement it once for all available languages. Though I don't know whether neovim's LSP does support this option at all. Moreover probably not all languages need such features as for example "find implementation (of an interface method)". Obviously because not all languages have interfaces.