Random ones requiring keep attributes for no reason on larger designs to keep stuff from being inferred away erroneously. Certain issues with limitations on SV interfaces only supporting constructs used in the "IP integration" scripting as opposed to the full language spec. I am sorry if I came off as overly negative, but I really think the FOSS EDA tools are going to lap them unless they open up somewhat.

I agree that just about all of the EDA tools are a pretty terrible experience.

I’ve gotten tired of dealing with quirks using SV interfaces in RTL. I’m using structs as a substitute at the moment.

(I am also biased because the designs I work on are small enough that ECP and presumably upcoming Lattice FPGAs are plenty. I am excited by the Xilinx reverse engineering efforts, too. But there seems to be less official interest than we see with Lattice in supporting the OSS efforts.)